Design and development of a physical layer mobile WiMAX ...

Design and development of a physical layer mobile WiMAX network simulation environment Final contract report Bob Szeker The scientific or technical validity of this Contract Report is entirely the responsibility of the contractor and the contents do not necessarily have the approval or endorsement of Defence R&D Canada.

Defence R&D Canada – Ottawa

Contract Report DRDC Ottawa CR 2009-239

January 2010

Design and development of a physical layer mobileWiMAX network simulation environmentFinal contract report

Bob Szeker

Prepared by:

nEW Technologies Inc.300 March Road, Suite 406, Kanata, Ontario, K2K 2E2

Project Manager: Jean-Francois BeaumontContract Number: W7714-050965/001/TORContract Scientific Authority: Jean-Francois Beaumont

The scientific or technical validity of this Contract Report is entirely the responsibility of the contractor and thecontents do not necessarily have the approval or endorsement of Defence R&D Canada.

Defence R&D Canada – OttawaContract Report

DRDC Ottawa CR 2009-239

January 2010

Scientific Authority

Original signed by Jean-Francois Beaumont

Jean-Francois Beaumont

Approved by

Original signed by Bill Katsube

Bill KatsubeHead/Communications and Navigation Electronic Warfare

Approved for release by

Original signed by Brian Eatock

Brian EatockChair/Document Review Panel

c⃝ Her Majesty the Queen in Right of Canada as represented by the Minister of NationalDefence, 2010

c⃝ Sa Majeste la Reine (en droit du Canada), telle que representee par le ministre de laDefense nationale, 2010

Abstract

This report details and summarizes the work performed in developing a computer simulationenvironment of the physical layer of a mobile WiMAX network. Since the work of WiMAXmodeling was first started in April of 2008, several developmental computer simulationmodels were created of increasing complexity, the results of which were published in a priorreport. The knowledge gained through these earlier simulation efforts were incorporatedinto the current simulation environment version.

The amount of effort required to unravel the complexities of WiMAX was considerablebut has produced an advanced simulation environment that is in accordance with theIEEE802.16e-2005 standard. The current version of the simulation environment refinesthe models previously developed with the addition of new functionalities and a GraphicalUser Interface (GUI) to facilitate the entry of the simulation parameters.

The computer simulation described in this report models both the physical layer and part ofthe media access layer of a WiMAX network. The report describes the software architectureto provide a better understanding of its components and includes detailed instructions onhow to setup and run the simulation.

Resume

Ce rapport decrit en detail et resume les travaux effectues pour le developpement d’un envi-ronnement de simulation informatique de la couche physique d’un reseau WiMAX mobile.Depuis que le travail de modelisation WiMAX a ete lance en avril 2008, plusieurs modelesde simulation informatique de complexite croissante ont ete crees, et dont les resultatsfurent publies dans un rapport precedent. Les connaissances acquises grace a ces travauxde simulation anterieurs ont ete integrees dans la version courante de l’environnement desimulation.

La quantite d’effort necessaire pour bien comprendre toute les complexites de la technologieWiMAX a ete considerable, mais a produit un environnement de simulation de pointe qui estconforme a la norme IEEE802.16e-2005. La version courante de l’environnement de simula-tion raffine les modeles developpes precedemment avec l’ajout de nouvelles fonctionnaliteset d’un interface graphique usager facilitant l’entree des parametres de simulations.

La simulation informatique decrit dans ce rapport modelise a la fois la couche physique etune partie de la couche de controle d’acces aux medias d’un reseau WiMAX. Le rapportdecrit l’architecture logicielle aidant a fournir une meilleure comprehension de ses compo-santes et fournit des instructions detaillees sur la facon de preparer et executer la simulation.

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Executive summary

Design and development of a physical layer mobile WiMAXnetwork simulation environment

Bob Szeker; DRDC Ottawa CR 2009-239; Defence R&D Canada – Ottawa; January 2010.

In order to support the Canadian Forces in the area of new and upcoming fourth generation(4G) wireless communications systems, the Defence Research and Development Canada- Ottawa (DRDC Ottawa) Modern Communications Electronic Warfare (MCEW) groupstarted an Applied Research Project (ARP) on emerging wireless systems. One particular4G standard of interest is the latest IEEE 802.16e-2005 standard known as WiMAX. In orderto support the research and development efforts to investigate this standard, the MCEWgroup started the development of computer simulation models of this new standard. Theintent of these models is to understand the signaling environment of this standard to beready to support present and future client needs in this emerging and quickly evolvingtechnology.

The task of developing simulation models started with the modeling of a fixed WiMAXsystem physical layer per the original IEEE 802.16-2004 standard. This effort led to a goodunderstanding of the key concepts and technologies employed by WiMAX. Several othersimulation models were produced of increasing complexity. The final models produced werebased on the IEEE 802.16e-2005 standard and simulated a mobile WiMAX physical layer.These computer models incorporated some of the advanced features inherent to mobileWiMAX systems. The simulation results gave an appreciation of how the performance ofthe WiMAX physical layer is dependent on the communications channel through whichsignals propagate.

This latest version of the simulation software, models both the downlink and uplink pro-cesses of a mobile WiMAX network. The simulation software models a simple WiMAXcell that can contain up to 6 mobile stations (subscriber stations). The physical channelbetween the base station and each of the mobile subscriber stations may be individuallydefined in terms of channel parameters and additive random noise. The simulation enablesa user to completely specify the WiMAX frame that is passed to the physical layer. In areal WiMAX system, this function is usually performed via the the data link (Media AccessControl (MAC)) layer. The physical layer model implements the required randomization,convolutional coding, interleaving, modulation, subcarrier mapping, and channel estimationprocesses defined by the WiMAX standard.

A graphical user interface provides the capability of simulating the higher-level media ac-cess control layer and provides control of the simulation environment. This software featuregreatly facilitates the setup of the WiMAX frame which includes the basic waveform pa-rameters, the frame preamble, the frame control header, the downlink and uplink maps, thesubcarrier permutation zones and the data bursts. The graphical user interface providesan ability to create an unlimited combination of WiMAX waveforms which will be essentialduring future laboratory testing.

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Sommaire

Design and development of a physical layer mobile WiMAXnetwork simulation environment

Bob Szeker ; DRDC Ottawa CR 2009-239 ; R & D pour la defense Canada – Ottawa ;janvier 2010.

Afin d’appuyer les Forces Canadiennes dans le domaine de la nouvelle et future quatriemegenenation (4G) de systemes de communications sans fil, le groupe Communications Mo-dernes Guerre Electronique (CMGE) de Recherche et Developpement pour la Defense Ca-nada - Ottawa (RDDC Ottawa) a debute un projet de recherche applique sur les systemessans fil emergeants. Une norme 4G d’interet particulier est la toute derniere norme IEEE802.16e-2005 mieux connue sous le nom de WiMAX. Afin d’appuyer les efforts de rechercheet developpement pour etudier cette norme, le groupe CMGE a debute le developpement demodeles de simulation par ordinateur pour ce nouveau standard. Le but de ces modeles estde comprendre l’environnement de signalisation de cette nouvelle norme pour etre pret asoutenir les besoins presents et futurs des clients sur cette technologie emergente qui evoluerapidement.

La tache visant a developper les modeles de simulation a commence avec la modelisation dela couche physique d’un systeme WiMAX fixe selon la norme IEEE 802.16-2004 d’origine.Cet effort a conduit a une bonne comprehension des concepts cles et des technologies em-ployes par WiMAX. Plusieurs autres modeles de simulation ayant des niveaux croissants decomplexite ont ete produits. Les modeles finaux produits ont ete bases sur la norme IEEE802.16e-2005 et ont servi a simuler la couche physique de la technologie WiMAX mobile.Ces modeles informatises ont integre des fonctionnalites avancees inherentes aux systemesWiMAX mobiles. Les resultats de simulation ont donne une idee sur la facon dont la per-formance de la couche physique WiMAX est dependante du canal de communication parlequel les signaux se propagent.

La derniere version du logiciel de simulation, modelise a la fois la liaison descendante etmontante d’un reseau WiMAX mobile. Le logiciel de simulation modelise une cellule Wi-MAX simple pouvant contenir jusqu’a 6 stations mobiles (stations d’abonnes). Le canalphysique entre la station de base et chacune des stations mobiles peut etre defini indivi-duellement en fonction des parametres du canal et l’ajout de bruit aleatoire. La simulationpermet a un utilisateur de specifier completement la trame WiMAX qui est passe a la couchephysique. Dans un vrai systeme WiMAX, cette fonction est habituellement effectuee parl’entremise de la couche de donnees (controle d’acces aux medias). Le modele de la couchephysique implemente la randomisation, le codage convolutif, l’entrelacement, la modula-tion, le mappage des sous-porteuses, et l’estimation de canal requis et definis par la normeWiMAX.

Un interface utilisateur graphique fournit le moyen de simuler le plus haut niveau de lacouche de controle d’acces aux medias ainsi que le controle de l’environnement de simulation.Cette caracteristique du logiciel facilite grandement la configuration de la trame WiMAX

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qui comprend les parametres de base de la forme d’onde, le preambule de la trame, l’en-tetedu controle de la trame, les mappages des liaison montante et descendante, les zones depermutation des sous-porteuses et les paquets de donnees. L’interface utilisateur graphiquefournit la capacite de creer un nombre illimite de combinaisons de formes d’ondes WiMAXqui seront indispensables au cours des essais en laboratoire a venir.

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Table of contents

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i

Resume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i

Executive summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Sommaire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Table of contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

List of figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

List of tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3 Graphical User Interface description . . . . . . . . . . . . . . . . . . . . . . . . . 4

3.1 Program menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.2 Setup menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.2.1 WiMAX waveform setup . . . . . . . . . . . . . . . . . . . . . . . 5

3.2.1.1 Nominal bandwidth control . . . . . . . . . . . . . . . . 5

3.2.1.2 Cyclic Prefix control . . . . . . . . . . . . . . . . . . . . 6

3.2.1.3 Frame duration control . . . . . . . . . . . . . . . . . . . 7

3.2.1.4 DL/UL subframe ratio control . . . . . . . . . . . . . . . 7

3.2.1.5 Preamble control . . . . . . . . . . . . . . . . . . . . . . 7

3.2.1.6 Frame Control Header control . . . . . . . . . . . . . . . 8

3.2.2 Overhead regions setup . . . . . . . . . . . . . . . . . . . . . . . . 8

3.2.3 Preamble setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.2.4 FCH setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.2.5 DL/UL zones setup . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.2.6 DL data bursts setup . . . . . . . . . . . . . . . . . . . . . . . . . 11

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3.2.6.1 The DL-MAP . . . . . . . . . . . . . . . . . . . . . . . . 13

3.2.7 UL data bursts setup . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2.7.1 The UL-MAP . . . . . . . . . . . . . . . . . . . . . . . . 17

3.3 Simulation menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

3.3.1 Setup command . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.3.1.1 Cell configuration setup panel . . . . . . . . . . . . . . . 19

3.3.1.2 The simulation panel . . . . . . . . . . . . . . . . . . . . 20

3.4 Run command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4 Simulation software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.1 Source files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.2 Software architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

5 WiMAX simulation example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

5.1 Scenario definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

5.2 Waveform setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

5.3 DL/UL data bursts setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

5.4 Simulation setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

5.5 Running the simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

List of acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

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List of figures

Figure 1: The PHY and MAC layers of a WiMAX network . . . . . . . . . . . . . 3

Figure 2: WiMAX GUI showing the waveform setup . . . . . . . . . . . . . . . . . 6

Figure 3: WiMAX GUI showing the zones setup . . . . . . . . . . . . . . . . . . . 10

Figure 4: WiMAX GUI showing the DL data bursts setup . . . . . . . . . . . . . 11

Figure 5: DL-MAP display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 6: WiMAX GUI showing the UL data bursts setup . . . . . . . . . . . . . 16

Figure 7: UL-MAP display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 8: The simulation GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 9: The channel property and description display . . . . . . . . . . . . . . . 21

Figure 10: The DL simulation panel . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 11: DL simulation results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 12: Simulation block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 13: Example simulation scenario . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 14: Example zone setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 15: Example data bursts setup . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Figure 16: Example simulation configuration . . . . . . . . . . . . . . . . . . . . . . 35

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List of tables

Table 1: Version 12 source files (A to D). . . . . . . . . . . . . . . . . . . . . . . . 25

Table 2: Version 12 source files (E to M). . . . . . . . . . . . . . . . . . . . . . . 26

Table 3: Version 12 source files (P to R). . . . . . . . . . . . . . . . . . . . . . . . 27

Table 4: Version 12 source files (S). . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Table 5: Version 12 source files (U to W). . . . . . . . . . . . . . . . . . . . . . . 29

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1 Introduction

This progress report summarizes the work performed in the design and development of aWiMAX network physical layer simulation model over the period of 1 February 2009 to31 October 2009. The work was performed under government contract number W7714-050965/001/TOR per Annex J of the Statement of Work.

The mobile WiMAX simulation model is coded using the Matlab language. The programexecutes in an interactive mode, providing the user control over a large number of param-eters through a graphical user interface (GUI). This graphical user interface is essentiallya pseudo-simulation of the higher-level media access control (MAC) layer. In the samecontext as the MAC-layer, the GUI is used to completely define the WiMAX waveform andeffectively to control what gets passed down to and up from the lower-level PHY layer.

The interactive nature of the program not only allows more straightforward control ofprogram operation but also facilitates learning about the complex WiMAX standard. Thesimulation offers online help and issues warning messages when operations are performedthat are inconsistent with the standard.

As the current version (V12) of the simulation has grown in both size and complexity,the report describes the software architecture and software components in detail. All GUIcontrols are described in detail to assist the user in operating the program.

This report is not intended to be a course on WiMAX. Although it presents considerableamount of information about WiMAX, it assumes that the reader is cognizant with thetechnologies used by WiMAX and the WiMAX standard.

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2 Background

The development of fixed and mobile WiMAX computer simulation models began in Aprilof 2008, whereby models of increasing complexity were produced. These initial programsmodeled only the PHY layer of a fixed network and were helpful in learning fundamentalWiMAX concepts. These earlier models were based on the IEEE802.16-2004 standard fora fixed WiMAX network. The models provided a solid understanding of the technologiesused by WiMAX and developed some of the basic software building-blocks.

During the previous reporting periods, the work focused on developing an accurate modelof a mobile WiMAX physical layer per the IEEE802.16e-2005 standard. The results ofthese effort were summarized in a Final Contract Report and submitted to the ScientificAuthority.

Previous simulation software versions initially modeled only the downlink (DL), which isfrom the base station (BS) to the mobile station (MS). A great deal of effort was expendedin developing and debugging code for the forward error correction (FEC) algorithms usedto encode and modulate the data at the transmitter, the channel model, and the receivermodel. Later software versions included the uplink (UL) from the mobile stations to thebase station.

At some point during the simulation model development it became evident that a graphicalinterface was needed to control program execution. This conclusion was arrived at becauseonce the PHY layer model was completed, a method was needed to specify the parametersthat get passed down to it. In an actual WiMAX network this task is performed by theMAC layer. As a complete modeling of the MAC layer was beyond the scope of the work,a GUI was the most logical way to specify the complex WiMAX waveform.

The PHY layer is basically a series of operations that processes the WiMAX frame beforeit is transmitted across the physical medium. It randomizes, convolutionally encodes, inter-leaves and modulates the signal, then maps it to carriers using several permutation modesdefined by the WiMAX standard. Before transmitting the signal a cyclic prefix is added tocombat multipath delay spread. At the receiver these steps are reversed.

The MAC layer basically controls the operation of the PHY layer. It specifies what getstransmitted and received on a single WiMAX frame, how the transmit and received databursts are structured, allocated, encoded, modulated, permutated, and so on. The choicesmade by the MAC layer are numerous and depend on several criteria. For example theMAC layer may change the type of modulation used or allocate different subchannels toan MS if the signal quality degrades. The MAC layer also implements higher system-levelcontrol by issuing several command and control messages to mobile subscriber stations.Higher-level layers that exist above the MAC layer are designated simply as HLL in Figure1.

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Figure 1: The PHY and MAC layers of a WiMAX network


3 Graphical User Interface description

During the course of development of the mobile WiMAX simulation environment the im-plementation of a graphical user interface (GUI) became necessary. A GUI was neededto define the WiMAX waveform that would normally be passed to the PHY layer by thehigher-level media access control (MAC) layer. In a WiMAX network, the waveform isdefined using MAC management messages and information elements (IE) such as the DCD,UCD, DL-MAP, UL-MAP and others. These MAC messages completely define the WiMAXframe and how it is to be interpreted by the receiving station.

The program can be launched by running the wimax GUI.m program. The GUI top-levelmenu contains the following drop down sub-menus:

PROGRAM - controls program state:EXIT - exits the WiMAX simulation.RESET - resets the simulation to its starting, default state.

SETUP - sets up different frame parameters:WAVEFORM - basic frame parameters setupOVERHEAD - subframe regions setup used for control bursts (i.e. DL-MAP)PREAMBLE - the frame preamble setupFCH - the frame control header setupDL/UL ZONES - the permutation zone switch setupDL DATA BURSTS - the downlink data regions setupUL DATA BURSTS - the uplink data regions setup

SIMULATION - controls the simulation state:SETUP - sets up parameters to be used for the simulationRUN - starts the simulationSTOP - indicates the end of a simulation run; not user selectable

VERSION - version informationSIMULATION - simulation version

The last top-level menu is the HELP menu. Selecting HELP displays a sub-menu of the cur-rent SETUP or SIMULATION selection. For example, when the program is first launchedthe WAVEFORM selection is active by default and is checked. Selecting Help->Waveformdisplays a short help message on the use of the waveform setup function.

The HELP message is displayed in a modal window and the simulation controls do notrespond to user inputs until the OK button is clicked.


3.1 Program menu

The Program top-level menu contains the Exit and Reset sub-menus. Clicking on ’Exit’closes the program. Clicking on ’Reset’ reinitializes the program to its default, startingconfiguration.

3.2 Setup menu

The top-level Setup menu allows specification of the WiMAX waveform, the overhead re-gions within the DL and UL subframes, the frame preamble and frame control header, theDL and UL subcarrier permutation zones, and the DL and UL data bursts. When thewimax GUI.m program is first launched, the waveform setup is entered and this selectionis checked in the top-level setup menu.

3.2.1 WiMAX waveform setup

The WiMAX waveform GUI enables the WiMAX waveform to be defined using the followingbasic parameters:

1. Nominal bandwidth (MHz). The WiMAX standard defines bandwidths of 1.25, 5.0, 10.0and 20.0-MHz. Four separate bandwidths exist to allow interoperation of WiMAXreceivers in different global regions. FFT sizes corresponding to these bandwidths are128, 512, 1024 and 2048 respectively. The simulation uses a default bandwidth of10.0-MHz (1024-point FFT size).

2. Cyclic prefix (CP) ratio. The WiMAX standard defines CP ratios of 1/32, 1/16, 1/8,and 1/4. The cyclic prefix is a method used to combat multipath delay spread.The simulation uses a CP of 1/8 by default.

3. Frame duration (msec). The WiMAX standard defines frame durations ranging from 2 to20 milliseconds. The frame duration time includes the DL subframe, TTG, UL subframeand RTG durations. The simulation uses a default frame duration of 5-msec.

4. DL/UL subframe ratio (%). The ratio can be varied from 20% to 80% by the simulation.By default a DL/UL ratio of 54% is used.

5. The frame number. The simulation allows the user to specify the frame number.By default the frame number is set to 1.

3.2.1.1 Nominal bandwidth control

When the wimax GUI.m program is first launched, the waveform setup shown in Figure 2is displayed. The waveform setup allows definition of the basic parameters described aboveusing the LHS control panel. When the nominal bandwidth is selected, the correspondingFFT size and subcarrier spacing are displayed. (Note that the subcarrier spacing is keptconstant at 10.937-KHz as specified by the WiMAX standard). As the nominal bandwidthis changed, the number of subcarriers that become available change, as well as the number of


Figure 2: WiMAX GUI showing the waveform setup

horizontal lines shown in the frame setup panel. The horizontal lines represents subchannelsconsisting of predetermined sets of subcarrier frequencies. (The allocation of subcarriers tosubchannels depend on the permutation mode used and discussed in a later section). Forexample, for a 10.0-MHz bandwidth, 1024-subcarriers are allocated to 30-subchannels. Fora 20-MHZ bandwidth, 2048-subcarriers are allocated to 60-subchannels, etc.

3.2.1.2 Cyclic Prefix control

The cyclic prefix (CP) ratio can be specified using the LHS control panel. The CP is theratio of the guard time to the useful symbol time and its purpose is to protect againstthe effects of multipath delay spread that degrades the signal quality. In signal processingterms, the tail portion of an OFDMA symbol is prepended to it after the IFFT operation andimmediately before to the signal is transmitted through the communications channel. Thecyclic prefix eliminates the inter-symbol interference which can occur in certain situationwhile maintaining transmitter coherency. The CP is removed at the receiver before theFFT is applied.

Changing the CP ratio has the effect of changing the number of OFDMA symbols thatare available within the WiMAX frame. This represents a tradeoff as the total number ofsymbols in the frame are reduced for the sake of signal quality gain.


3.2.1.3 Frame duration control

The WiMAX frame duration can be specified using the LSH control panel. By defaultthe frame duration is set to 5-msec. Increasing the frame duration increases the numberof OFDMA symbols available. The DL/UL subframe ratio allows the user to specify thenumber of OFDMA symbols contained in the DL and UL subframes respectively.

OFDMA symbols are represented by vertical gray lines within the frame setup panel. Bydefault, the simulation defines a single permutation zone for the DL subframe and a singlepermutation zone for the UL subframe. The end of each zone is marked by a vertical dashedwhite line. Per the WiMAX standard, the 1st DL zone must be PUSC (partial usage ofsub-carriers). In WiMAX, the basic data allocation unit is a slot. For DL PUSC each slotconsist of 2-OFDMA symbols, whereas for UL PUSC a slot consists of 3-OFDMA symbols.Slot boundaries are shown as vertical red dashed lines in the frame setup panel.

3.2.1.4 DL/UL subframe ratio control

The DL/UL subframe ratio can be controlled using the LHS control panel. It is set at54% by default. When the DL/UL ratio is changed in the LHS control panel, the programrecalculates the number of slots in each subframe to be an integral multiple. RemainingOFDMA symbols that cannot be allocated to slots are removed and their times are as-signed to the transmitter turnaround gap (TTG) or receiver turnaround gap (RTG) timesrespectively.

3.2.1.5 Preamble control

Within the frame panel, the yellow area represents the frame preamble which is always1-OFDMA symbol wide. The preamble is always transmitted and marks the beginning ofthe WiMAX frame. The preamble contains information vital to the receiver in order torecover and decode the signal. The receiving subscriber stations use the frame preambleto perform a channel estimate, without which the signal stands very little chance of beingcorrectly recovered. The preamble is transmitted with a nominal boost of 9-dB and useshighly reliable BPSK modulation. This assures that the preamble can be extracted at thereceiver even in a badly degraded channel environment.

The preamble is used to transmit pseudo-noise (PN) sequences that encode the cell ID foreach segment when segmentation is used. Cell IDs ranging from 0 to 31 can be assigned toeach segment. The WiMAX standard defines PN sequences for each bandwidth. Three PNsequences are used to modulate the preamble carrier frequencies, specifying the cell ID foreach of the three segments. The first PN sequence modulates subcarriers 1,4,7,..., the sec-ond sequence modulates subcarriers 2,5,8,..., and the third sequence modulates subcarriers3,6,9,...etc.

Clicking on the preamble (yellow) region within the frame panel opens the preamble controlpanel where the user can specify the preamble boosting and the cell IDs for each segment.


3.2.1.6 Frame Control Header control

The magenta region in the frame panel represents the frame control header (FCH) whosesize varies based on the selected bandwidth. The FCH is displayed automatically by thesimulation and is drawn inside the gray region within the DL subframe. This gray regionis an area within the DL subframe reserved for the FCH, DL-MAP, UL-MAP and otherMAC management messages, and is referred to as the frame ’overhead’ region.

The FCH is always positioned starting with a subchannel offset of 0 and is 1-slot wide. Forbandwidths other than 1.25-MHz, a 24-bit FCH is formed and repeated over 4 subchannelsforming a 48-bit block. For 1.25-MHz operation, a reduced 12-bit FCH is formed andrepeated over 4 symbols forming a 48-bit block. The FCH is used to convey information onthe subchannel groups used, the repetition coding and coding type used on the DL-MAP,and the length of the DL-MAP.

Clicking on the FCH (magenta) region within the frame panel opens the FCH control panel.The FCH control panel for the current simulation version (V12.0) allows only the selectionof the subchannel groups used, however the simulation does not use segmentation. Althoughthe subchannel groups can be specified, they are not used when the FCH is decoded bythe receiver. No repetition code is used on the DL-MAP and the coding type defaults toconvolutional coding (CC). The simulation program inserts the DL-MAP length (in slots)into the FCH automatically.

3.2.2 Overhead regions setup

Clicking on Setup->Overhead regions in the top-level menu opens a LHS control panel. Thispanel can be used to specify the DL and UL overhead regions located in the DL and ULsubframes respectively. By default the simulation sets the DL overhead to be 5-OFDMAsymbols. No UL overhead is allocated (0-OFDMA symbols allocated by default).

As mentioned in Section 3.2.6, the overhead region is shown in the subframe as a gray area,and contains the preamble, FCH, DL-MAP and UL-MAP. This gray area is considered asoverhead, since it contains entities that carry only control data. Since resources must beallocated to these control regions, the bandwidth available for data regions is reduced.

As described in a following section, regular data bursts carrying user data cannot be allo-cated inside the overhead regions. Allocations within the overhead regions are reserved forthe simulation program and occur automatically.

3.2.3 Preamble setup

Clicking on Setup->Preamble in the top-level menu opens a LHS control panel. Alternatelythe preamble setup control panel can be opened by clicking on the (yellow) preamble regionwithin the frame panel. For the description of the preamble setup panel see Section 3.2.5.


3.2.4 FCH setup

Clicking on Setup->FCH in the top-level menu opens a LHS control panel. Alternativelythe FCH setup panel can be opened by clicking on the (magenta) FCH region within theframe panel. For the description of the FCH setup panel see Section 3.2.6.

3.2.5 DL/UL zones setup

Clicking on Setup->DL/UL Zones in the top-level menu opens the DL zone setup and ULzone setup control panels on the LHS.

As specified by the WiMAX standard, both the DL and UL subframes may contain severalpermutation zones. For the DL, 5 zone switches are allowed and for the UL, 3 zone switchescan occur . The first DL zone must be PUSC (partial usage of subcarriers), which maybe followed by other PUSC, FUSC (full usage of subcarriers), OFUSC (optional FUSC) orAMC (adaptive modulation and coding) permutation zones. There is no restriction on ULzones; any of the 3 zones may be PUSC, OPUSC (optional PUSC) or AMC permutationzones.

In the DL zone setup panel the 1st zone is therefore set to be PUSC and the control isdeactivated. By default the 1st UL zone is also set to be PUSC but can be changed toOPUSC or AMC.

Unlike the controls described in preceding sections, the frame panel becomes ’active’ whenthe DL/UL zone setup is selected. Zones can be created by clicking within the frame panel.Since zone boundaries must start and end on integer multiples of slots, zones can only becreated by clicking on the red, vertical, dashed lines. Zone boundaries thus created areshown as white, vertical dashed lines. When a zone boundary line is clicked, the zonelocated to the right of it is deleted. The OFDMA symbols that become available from thedeleted zone are added to the previous zone.

For both DL and UL subframes the newly created zone is set to PUSC permutation bydefault. The zone permutation can then be changed using the LHS control panel. Thecontrol panel shows the number of subchannels and symbols contained in the zone for thepermutation mode. Horizontal lines representing subchannels are redrawn based on thepermutation mode specified.

Figure 3 shows an example zone setup. A total of 5-OFDMA symbols are reserved for theDL overhead region. The 1st DL zone is PUSC by default and contains 8-OFDMA symbols,not including the frame preamble. A total of 4-OFDMA symbols (2-slots) are available foruser data region allocation. The 1st DL zone contains 30-subchannels.

The 2nd DL zone is defined as an AMC (3x2) zone with 4-OFDMA symbols (2-slots)available. AMC allocations differ from PUSC and FUSC allocations. The basic AMCallocation unit is a ’tile’ as opposed to a ’slot’. There are 3 types of AMC tiles. A tilecan be 1x6, 2x3 or 3x2 (subchannels by symbols). The program automatically selects theappropriate AMC tile configuration based on the number of OFDMA-symbols available in


Figure 3: WiMAX GUI showing the zones setup

the zone. If a zone consists of a multiple of 6-symbols, AMC tile configuration can be anyone of 1x6, 2x3 or 3x2.

The 3rd DL zone is defined as a FUSC zone with 2 OFDMA-symbols (2-slots) available.Note that a FUSC slot contains 48-subcarriers, whereas a PUSC slot contains only 24-subcarriers. Hence 2-OFDMA symbols are required to form a PUSC slot whereas only1-OFDMA symbols is needed for a FUSC slot. The FUSC zone contains 16-subchannels.

The 4th zone is defined as another PUSC zone and the 5th (last) zone is an AMC (1x6)zone.

The UL zones are AMC (2x3), PUSC, and AMC (1x6). Note that an UL PUSC slot ismade up of 3-OFDMA symbols whereas a DL PUSC slot contains only 2-symbols.

Although the GUI allows the creation of various zone switches, the current version (V12) ofthe simulation is limited to using PUSC or FUSC for the DL and PUSC for the UL. Subcar-rier permutations for OFUSC, OPUSC and AMC have not been implemented. Specifyingpermutation modes not currently supported will lead to unpredictable program behavior.


3.2.6 DL data bursts setup

Clicking on Setup->DL Data bursts in the top-level menu opens the DL data bursts setuppanel on the LHS. The LHS control panel changes to allow various parameters pertainingto the 1st DL data burst to be configured. The controls are desensitized until the burst iscreated in the DL subframe.

DL data bursts are regions within the DL subframe that are allocated to specific connectionIDs. These data bursts contain information (i.e. data, voice, video, etc) intended for a singleuser, several users or all users.

As with the zone setup control described in the previous section, the frame panel becomes’active’ when the DL data regions setup control is selected. Clicking and dragging themouse within the frame panel designates the location of the burst in terms of symbol andsubchannel offsets and counts. This type of allocation is referred to as ’block-type’ allocationand is the only allocation type used within the DL subframe. As will be seen in the nextsection, UL burst allocation can be either block or duration-type.

Figure 4: WiMAX GUI showing the DL data bursts setup

Figure 4 shows a hypothetical DL data bursts setup example. Three DL zones are defined;the 1st DL PUSC zone, the 2nd FUSC zone and the 3rd PUSC zone. A total of 10 databursts were created spread across all zones. The data burst were created by clicking and


dragging the mouse. Data bursts must start and end on slot boundaries else a warningmessage is issued by the program and the burst is not created. Data burst may be createdin any order. Existing bursts can be selected by double-clicking the left mouse button(LMB) on the bursts. This action changes the LHS panel to display the parameters of theselected burst. An existing burst can be deleted by clicking the right mouse button (RMB)on the burst.

As shown in Figure 3 example, burst #1 was selected . The LHS control panel changesto display the burst parameters. The DIUC (downlink interval usage code) specified forburst #1 is QPSK (CC) 1/2 which describes the modulation, coding type and coding rateapplied to this burst. DIUCs with QPSK, 16-QAM and 64-QAM may be specified with CCor BTC coding types and various coding rates. The current version of the simulation (V12)however only supports the CC coding type. DIUCs with BTC coding type should not beselected.

The DUIC drop list allows the user to specify indices from 0 to 15 for each burst, howeveronly indices 0 to 12 should be used. DIUC index 13 (Gap/PAPR reduction), index 14(extended-2 DIUC), and index 15 (extended DIUC) will cause the program to generate a’not implemented’ warning message. (The simulation generates some of these DIUC indicesautomatically. For example when a DL permutation zone changes, the simulation generatesa special IE in the DL-MAP with DIUC index 15. This will be discussed in a later section).

The data burst can be assigned to a maximum of 6 different users or CIDs. ConnectionIDs must be specified using 4 hexadecimal characters, for example 0xaaaa, 0x3e4f, etc. Theprogram verifies the CID string and generates warning messages if incorrect. For example,warning messages are generated if an invalid hex character is entered or an incorrect numberof characters are specified. The CID is only assigned to the burst when the pushbuttonlocated to the right of the CID is pressed. The pushbutton then changes to green indicatingthat it has been assigned to the burst. If the CID has already been assigned to the burst,the program generates a warning message and the CID string is cleared.

To simplify CID assignments, the control panel contains a pushbutton labeled ’AUTO’which automatically specifies and assigns default CIDs to the data burst. The default CIDsused are 0xaaaa through 0xffff. As shown in a following section, subscriber station IDscan be assigned in a similar manner, whereby SS#1 is assigned a CID of 0xaaaa, SS#2 isassigned a CID of 0xbbbb, etc. Since the actual CIDs used is irrelevant to the simulation,the automatic allocation of CIDs helps to speed up the simulation setup process.

The symbol and subchannel offsets and counts for data burst #1 are shown below the CIDcontrols. These parameters are shown here for reference only and completely describe thelocation of the burst in the DL subframe. The symbol and subchannel offsets and countsare used by the receiving SS to locate the burst and is an example of block-type burstallocation.

The UBS field shows the uncoded block size of the data burst. The UBS is the amountof raw data in bytes that can be accommodated by the burst and depends on the DIUC


specified. As the modulation and coding rate is increased, more data can be packed intothe same burst. For example, the number of slots assigned to data burst #1 is 11, themodulation is QPSK therefore the number of coding bits used per carrier is 2, and thecoding rate is 1/2. The UBS is calculated as:

UBS = (11 * 48 * 2 * 1/2) / 8 = 66 bytes

If 64-QAM modulation is specified for the same burst while keeping the coding rate thesame:

UBS = (11 * 48 * 6 * 1/2) / 8 = 198 bytes

since 64-QAM uses 6 coding bits per carrier. The amount of raw data that can be trans-mitted with the same burst increases, however this type of modulation is more susceptibleto noise and intersymbol interference and is therefore more prone to bit errors.

In Figure 3, the SCPM field shows the subcarrier permutation used for the burst. Sinceburst #1 is located in the 1st DL zone the SCPM is PUSC. The data burst setup panelshows the SCPM for reference only.

Per the WiMAX standard a DL data burst may be boosted and repeated. The DL databurst setup panel includes drop lists to specify the associated boosting and repetition codevalues. By default the burst is not boosted (or attenuated), but values of +6, -6, +9, +3, -3,-9 and -12 dB may be specified. Similarly, by default the burst is not repeated, but valuesof 2, 4 or 6 repetition codes may be specified. Repetition codes can only be specified forQPSK modulated bursts. The program generates a warning message otherwise and resetsthe modulation type to QPSK (DIUC index 0). Even though these GUI controls exist, thecurrent version (V12) of the program does not support boosting or repetition of DL databursts.

The TX DATA drop list in the DL data burst setup panel allows the user to specify thetype of data to be contained in the burst. Transmit data types of random, video and audiocan be selected, however the current version (V12) of the program uses only random data.

The BSID field allows the specification of the base station ID. The BSID is a 48-bit field setby default to 0x0000DEADBEEF. The BSID is encoded in the DL-MAP message discussedin a later section. The BSID can be changed by the user, but it has no consequenceon the current program’s operation. Future versions of the program may use it for theimplementation of new features.

3.2.6.1 The DL-MAP

The DL-MAP is a MAC management message that is generated automatically by the pro-gram as DL data bursts are created (or deleted) in the DL subframe. The DL-MAP isshown as a green region in the DL overhead region and follows immediately after the FCH.The DL-MAP encodes the parameters of each data burst (i.e. the symbol and subchanneloffsets and count, DIUC, CIDs, repetition code, boosting, etc). The set of parameters for


each data burst created in the DL-MAP is called an information element (IE). The DL-MAP is used by the receiving SS to determine the burst locations within the DL subframeand to extract the associated modulation and coding types.

The DL-MAP can also contain zone switch IEs when permutation zone switches are definedin the DL subframe. The simulation automatically generates zone switch IEs (DIUC index15) and inserts these within the DL-MAP.

Clicking on the green DL-MAP region in the DL subframe of Figure 4 displays a shortdescription of the DL-MAP as shown in 5.

Figure 5: DL-MAP display

Figure 5 shows a summary of the DL-MAP. It displays the length of the map which isalways rounded to the nearest byte boundary. The DL-MAP always contains a MACmessage header.

The first IE of the DL-MAP always contains the UL-MAP parameters. In this case noUL data bursts have been allocated yet therefore the IE is empty. The following entriesdescribe the various zone switches and DL data burst IEs. The 1st PUSC zone contains 3IEs, one for each data burst in the 1st zone. The first data burst has 3 CIDs assigned, the2nd and 3rd has only 1 CID. This is followed by a zone switch IE containing 4 data bursts.Finally, another zone switch IE follows containing 3 data bursts.


3.2.7 UL data bursts setup

Clicking on Setup->UL Data bursts in the top-level menu opens the UL data bursts setuppanel on the LHS. The LHS control panel changes to allow various parameters pertainingto the 1st UL data burst to be configured. The controls are desensitized until the burst iscreated in the UL subframe.

UL data bursts are regions within the UL subframe that are allocated to a specific connectionID. UL data bursts contain any type of data an SS wishes to transmit.

As with the DL data burst setup control described in the previous section, the frame panelbecomes ’active’ when the UL data regions setup control is selected. Instead of block-typeburst allocation, the UL data bursts setup uses duration-type burst allocation by default.Instead of clicking and dragging the mouse within the frame panel to allocate a burst,the data burst is allocated by clicking the LMB on a slot boundary. Slot boundaries areshown as red, vertical dashed lines. Slots are allocated starting with the lowest subchanneland lowest OFDMA symbol then increased across the symbols to the zone boundary, thenstarting at the next subchannel.

A DL-MAP must exists before any UL data bursts can be allocated in the UL subframe.The DL-MAP is a green region in the DL overhead region and located immediately afterthe FCH and is generated automatically by the program. The UL-MAP is a blue region inthe DL overhead region and located immediately after the DL-MAP. The UL-MAP is alsogenerated automatically by the program when UL data bursts are allocated. Hence if noDL-MAP exists the program issues a warning message.

The UL data bursts setup allows the user to select between block and duration-type allo-cations, however only the latter is currently supported. Block-type UL allocations are forspecial burst allocations which include UIUC 0 (fast-feedback channel), UIUC 12 (CDMABW request & ranging), and UIUC 13 (PAPR reduction & safety zone) and are not sup-ported by the current program version.

Duration-type UL data burst allocations include UIUC 1 to 10 for burst profiles, UIUC 11(extended-2 UIUC), UIUC 14 (CDMA allocation), and UIUC 15 (extended UIUC). OnlyUIUC indices 1 to 10 are supported and the program will generate a warning messageotherwise. Furthermore UIUC indices with BTC coding types should not be specified asBTC coding type is not supported by the current software version.

Figure 6 shows a hypothetical UL data bursts setup example. Two UL zones are defined;the 1st UL PUSC zone and the 2nd AMC (1x6) zone. There is no limitation on the 1stzone; it can be PUSC, OPUSC or AMC. A total of 10 data bursts were created within theUL subframe. Data bursts must start and end on slot boundaries else a warning messageis issued by the program and the burst is not created. Data burst may be created in anyorder. Existing bursts can be selected by clicking the left mouse button (LMB) on thebursts. This action changes the LHS panel to display the parameters of the selected burst.An existing burst can be deleted by clicking the right mouse button (RMB) on the burst.Data burst 2, 6 and 8 were deleted in this example by clicking the RMB.


Figure 6: WiMAX GUI showing the UL data bursts setup

As shown in Figure 6 example, burst #1 was selected . The LHS control panel changes todisplay the burst parameters. The UIUC (uplink interval usage code) specified for burst #1is QPSK (CC) 1/2 which describes the modulation, coding type and coding rate applied tothis burst. UIUCs with QPSK, 16-QAM and 64-QAM may be specified with CC or BTCcoding types and various coding rates. The current version of the simulation (V12) howeveronly supports the CC coding type. UIUCs with BTC coding type should not be selected.

Unlike DL data bursts which can have multiple CIDs assigned for multicast or broadcastoperation, UL data burst have only a single CID assigned. Each UL burst is dedicated toone and only one user. In the example of Figure 6, the CID field for burst #1 is empty asit has not been assigned to an SS. The CID assigned must be specified as 4 hexadecimalcharacters before the pushbutton (located to the right of the field) is pressed. If the CID iscorrect the pushbutton changes to green indicating that the CID has been assigned, else awarning message is generated.

The UL data burst setup panel contains two regions below the CID field that show thelocation of the data burst. The first region is for block-type allocations and shows thepertaining subchannel and symbol offsets and counts. The second region is for duration-type allocations and shows the duration and offset in slots. In the example of Figure 6,data burst #1 has an offset of 0-slots and a duration of 18-slots. Offsets are referenced tothe zone the bursts is located in. Both of these regions in the LHS setup panel are shownfor reference only.


The UBS field shows the uncoded block size of the data burst. The UBS is the amountof raw data in bytes that can be accommodated by the burst and depends on the UIUCspecified. As the modulation and coding rate is increased, more data can be packed intothe same burst. For example, the number of slots assigned to data burst #1 is 18, themodulation is QPSK therefore the number of coding bits used per carrier is 2, and thecoding rate is 1/2. The UBS is calculated as:

UBS = (18 * 48 * 2 * 1/2) / 8 = 108 bytes

If 64-QAM modulation is specified for the same burst while keeping the coding rate thesame:

UBS = (18 * 48 * 6 * 1/2) / 8 = 324 bytes

since 64-QAM uses 6 coding bits per carrier. The amount of raw data that can be trans-mitted with the same burst increases, however this type of modulation is more susceptibleto noise and intersymbol interference and is therefore more prone to bit errors.

In Figure 6, the SCPM field shows the subcarrier permutation used for the burst for refer-ence only. The SCPM depends on the zone that the UL burst is located in.

Per the WiMAX standard a UL data burst may be repeated. No boosting is applied to ULbursts. The UL data burst setup panel includes drop lists to specify the associated repetitionvalue. By default the burst is not repeated, but values of 2, 4 or 6 repetition codes may bespecified. Repetition codes can only be specified for QPSK modulated bursts. The programgenerates a warning message otherwise and resets the modulation type to QPSK (UIUCindex 1). Even though a GUI control exist, the current version (V12) of the program doesnot support repetition of UL data bursts.

The AST filed in the UL data burst setup panel specifies the allocation start time for theburst. The AST is specified in terms of physical slot (PS) units. Although the AST for aburst can be specified the program currently does make use of it. As described in a latersection, the AST is a quantity required by the UL MAP.

3.2.7.1 The UL-MAP

The UL-MAP is a MAC management message that is generated automatically as UL databursts are created (or deleted) in the UL subframe. The UL-MAP is shown as a blue regionin the DL overhead region and follows immediately after the DL-MAP. The UL-MAP isused to encode the parameters of each data burst (i.e. the slot offset and count, UIUC, CID,repetition code, etc). The set of parameters for each data burst created in the UL-MAP iscalled an information element (IE). The UL-MAP is used by the SS to determine the burstlocations of the burst(s) and to determine the associated modulation and coding types.

The UL-MAP can also contain other IE types such as zone switches when permutation zoneswitches are defined in the DL subframe. The program automatically generates zone switchIEs (UIUC index 15) in the UL-MAP.


Clicking on the blue UL-MAP region in the DL overhead region displays a short summaryof the UL-MAP as shown in Figure 7.

Figure 7: UL-MAP display

The UL-MAP information display shows the length of the map which is rounded to thenearest byte boundary. The UL-MAP always contains a MAC message header.

The first 5 IEs of the UL-MAP are in the 1st zone. Since these IEs are not preceded by azone switch IE, the zone defaults to PUSC permutation mode. Each IE displays the CIDassigned to the burst. Note that in this example the SS with CID 0xaaaa has 2 IEs (2bursts) assigned to it. The 1st PUSC zone is followed by a 2nd zone for which the SCPM isdefined by the switch IE. The 2nd zone contains 2 data bursts. These bursts are assignedto SS’s with CIDs 0xcccc and 0xeeee respectively.

3.3 Simulation menu

The top-level Simulation menu contains the Setup, Run and Stop commands. Clicking on’Setup’ changes the GUI from the waveform setup configuration to the simulation setupconfiguration. Clicking on ’Run’ runs the simulation. The ’Stop’ command is alwaysdesensitized and cannot be selected by the user. Its sole purpose is to indicate the endof a simulation run at which point it becomes checked. The user should first select ’Setup’and define the various simulation parameters before running the simulation.

The simulation results are displayed in the main control panel (MCP) located at the bottom.The MCP contains the simulation status and simulation results sub-panels.

As the simulation runs it displays status messages which can be later inspected usingthe scroll bar. The status messages output by the simulation can be used for program


debugging and verification purposes. The status messages also help understand the varioussteps performed by the simulation.

The bit-error-rate (BER) results for both the DL and UL are displayed in the simulationresults sub-panel. During DL processing the bit error rates for DL data bursts are displayed.Similarly, UL data burst bit error rates are displayed during UL processing. After thesimulation is complete, clicking anywhere within the simulation results sub-panel togglesthe DL and UL BER results.

3.3.1 Setup command

Clicking on ’Setup’ in the top-level Simulation menu changes the display as shown in Figure8. The GUI contains the configuration panel on the LHS, the simulation panel, and theMCP.

3.3.1.1 Cell configuration setup panel

The LHS cell configuration setup panel is used to specify the cell IDs of the subscriberstations located in each cell segment. Cell IDs can be any 16-bit quantity, specified using4 hexadecimal digits. The program verifies that the cell ID specified is correct, else awarning message is generated. To simplify the simulation setup, the AUTO pushbuttonautomatically assigns CIDs as 0xaaaa to SS #1, 0xbbbb to SS #2, etc. If an SS is notassigned a CID it will be incapable of processing DL or UL data bursts; it will simplyinterpret that none of the transmissions from the BS are intended for it. If none of the SS’sare assigned CIDs the simulation issues a message warning of this condition and stop. (Ifthe simulation were to continue it would appear that nothing is happening as there wouldbe zero data transfer condition. In fact, each SS would still be active, decoding the receivedsignal and discovering that none of the data burst are assigned to it).

The simulation uses SUI (Stanford University Interim) channels to model the communi-cations media through which signals propagate. There are 6 SUI channels available forselection. The 6 SUI channels are adequate to model the various rural and urban environ-ments that may be encountered by the signal. Each SUI channel also has an associatedreset count to generate a specific instance of the channel. This is necessary as the channel isnot a static quantity but whose parameters change with time. The variation of the channelwith time is brought about by the dynamic nature of the channel in which the subscriberstations themselves are mobile, as are the other scattering elements in the channel.

The LHS cell configuration panel is also used to specify the signal-to-noise ratio (SNR) foreach cell segment. By default an SNR of 60-dB is assigned to each segment. A drop listcan be used to specify SNR as low as 10-dB. The simulation adds white Gaussian noise tothe signals propagating between the BS and the SS at the SNR level specified.


Figure 8: The simulation GUI

3.3.1.2 The simulation panel

The simulation panel is divided into two areas. The first area shows an idealized, hexagonalcell divided into 6 segments with a single SS is located in each. SS #1 is located in segment1, SS #2 is located in segment 2, etc. In a realistic scenario, a WiMAX cell will contain afar greater number of subscriber stations. For the sake of simplicity the simulation limitsthe number of subscriber stations per cell to 6.

Each cell segment represents a communications channel whose properties may be identicalto, or quite different from adjacent segments. The properties of the cell segment can beconfigured using the LHS cell configuration panel.

The RHS display in the simulation panel displays the communications channel propertiesfor the selected cell segment. The plots show the relative path gains vs. path delays andthe channel magnitude frequency response. These plots are generated when the user clickson one of the cell segments. The plots are also generated if the SUI channel number or thechannel reset count values are changed in the LHS cell configuration panel.

For example, if cell segment 1 (containing SS #1) is clicked, an instance of SUI channel isgenerated. The plots displayed in Figure 9 show the instantaneous properties of the com-munications channel between the BS and SS #1. Clicking on the green channel descriptionbutton displays the channel description.


Figure 9: The channel property and description display

The relative path gains vs. path delays plot shows the normalized transmitted signal andthe secondary (reflected) signals caused by the multipath effect. The delayed multipathsignals will sum constructively or destructively with the main signal at the receiver. Theircombined effect is shown by the channel magnitude frequency response plot. It shows howthe various subcarrier frequencies are attenuated over the signal bandwidth.

Data bursts whose carrier frequencies are concentrated within regions of deep signal fadeswill be difficult to recover. As mentioned previously, the first task of the receiver is toperform a preamble-based channel estimate. It is of utmost importance to successful signalrecovery to correctly estimate the channel and to apply this estimate to each OFDMAsymbol. (The method of recovering the received symbols using the channel estimate assumesthat the channel properties remain relatively constant during the frame time).

3.4 Run command

Clicking on ’Run’ in the top-level Simulation menu runs the simulation. It is assumedthat the WiMAX waveform has been defined and the simulation parameters have beenconfigured as described in the previous sections.

The program currently simulates a single DL transmission from the BS to the SSs in thecell, which is then followed by a single UL transmission from each SS to the BS. (Futuresoftware versions will allow more control over the simulation, such as the number of DLand UL cycles).

While the DL simulation is running, status messages are displayed in the simulation statussub-panel of the MCP. Several status, warning and/or error messages are displayed by


each SS, located in the cell segments as shown in Figure 10. It is not possible to stop thesimulation once it has been started and it should be allowed to run to completion.

The RHS simulation panel changes to display the channel estimate results for each cellsegment. The original signal’s frequency response curve is shown in blue and the channel’sfrequency response is shown in red. The final estimated signal is shown in white. A goodchannel estimate is indicated by a flat signal frequency response curve that is free of deepfades or peaks. Examples of good channel estimates are those obtained for SS #4, #5 and#6.

Figure 10: The DL simulation panel

In the example shown in Figure 10, SS #3 was unable to extract the FCH from the receivedframe due to the degraded channel. As shown in the RHS plot for SS #3, a perfect channelestimate could not be determined for the SUI #4 channel. In this case the frame is dropped(ignored) by the SS. The other subscriber stations all successfully decode the frame, extractthe DL data bursts and complete DL processing. The simulation status and simulationresults are shown in the MCP per Figure 11.

Figure 11: DL simulation results


The simulation status panel in the MCP lists the DL processing steps. The list can bereviewed and examined using the scroll bar. The simulation results panel shows the BERscalculated for each DL data burst. From this example it can be seen that DL burst #1was broadcast to all subscriber stations. No burst was processed by SS #3 due to an FCHdecoding error. All other SS’s received burst #1 without error. The results panel also showsthat burst #1 was QPSK modulated. All other burst were unicast messages, intended fora single SS. The BER is highest for 64-QAM modulated bursts (0.35 and 0.21 % for bursts#6 and #7 respectively).


4 Simulation software4.1 Source files

The Matlab source files for simulation Version 12 are shown in alphabetical order in Tables1 to 5. The main program is contained in the wimax GUI.m file.


File # File name Description Size (Kb)

1 add DL zone called by setup zones (84) 21

2 add UL zone called by setup zones (84) 6

3 amc event fcn called by AMC event callback handler 8in wimax GUI (101)

4 amc subchans fcn - not used - 12

5 AST event fcn called by AST callback event handler 2in wimax GUI (101)

6 binary2hex called by generate DL MAP (41) 2and info DLULMAP msg (50)

7 bit symbol called by map (54) 4

8 boosting event fcn called by boosting event callback 3handler in wimax GUI (101)

9 BSID event fcn called by BSID callback event handler 2in wimax GUI (101)

10 BStoSS xmit wavefront called by wimax GUI (101) 7

11 calc frame panel params called by wimax GUI (101), 9x 7

12 calc ubs called by diuc event fcn (26), 9uiuc event fcn (93),setup DL data regions (81),setup UL data regions (83)

13 channel estimate pb called by simulation DL (87) 6

14 constellation parameters called by map (54) 2

15 cyclic called by simulation DL (87), 3simulation UL (89)

16 datatype event fcn called by datatype event callback 3handler in wimax GUI (101)

17 decode DL MAP msg called by simulation DL (87) 23

18 decode UL MAP msg called by simulation DL (87) 15

19 delete DL zone called by setup zones (84) 21

20 delete UL zone called by setup zones (84) 11

21 determine FFT size - not used - 4

22 determine NFFT and CP called by simulation DL (87) 4

23 disable cell config cntls called by simulation DL (87) 2

24 display DLUL maps called by several event handlers in 8wimax GUI (101), simulation DL (87)

25 display status msg called by decode DL MAP msg (17), 2decode UL MAP msg (18),simulation DL (87), simulation UL (89)

26 diuc event fcn called by DIUC event callback handler 4in wimax GUI (101)

Table 1: Version 12 source files (A to D).



27 enable cell config cntls called by mh1 callback handler in 2wimax GUI (101), simulation setup (88)

28 estimatechannel called by channel estimate pb (13) 3

29 find index called by bit symbol (7) 2

30 find preamble 128 called by simulation DL (87) 12




34 find UL data start called by setup UL data regions (83) 5

35 form preamble 128 called by simulation DL (87) 10




39 frameno event fcn called by frameno callback handler 3in wimax GUI (101)

40 generate DL databurst IE called by generate DL MAP (41) 3

41 generate DL MAP called by several event handlers 17in wimax GUI (101)

42 generate DL Zone Switch IE called by generate DL MAP (41) 5

43 generate fading chan called by several event handlers 5in wimax GUI (101)

44 generate UL databurst IE called by generate UL MAP (45) 2

45 generate UL MAP called by several event handlers 12in wimax GUI (101)

46 generate UL Zone Switch IE called by generate UL MAP (45) 3

47 gensubchan DL called by simulation DL (87) 4

48 gensubchan UL called by simulation UL (89) 4

49 help msg handler called by mh5 callback handler 19in wimax GUI (101)

50 info DLULMAP msg called by DL MAP callback and 17UL MAP callback handlersin wimax GUI (101)

51 init frame panel called by several event handlers 11in wimax GUI (101)

52 init regions called by several event handlers 2in wimax GUI (101)

53 interleaving called by simulation DL (87) 4

54 map called by simulation DL (87) 6

Table 2: Version 12 source files (E to M).



55 parameters SUI called by generate fading chan (43), 3simulation DL (87)

56 pb BW event fcn called by pb BW callback handler 14in wimax GUI (101)

57 pb CID event fcn called by pb CID callback handler 10in wimax GUI (101)

58 permode event fcn called by permode event callback handler 35in wimax GUI (101)

59 process cntl click fcn called by frame panel event callback 8handler in wimax GUI (101)

60 process dble click fcn called by frame panel event callback 3handler in wimax GUI (101),setup UL data regions (83)

61 process DIUC called by simulation DL (87) 4

62 process UIUC called by simulation UL (89) 3

63 process UL mapping matrix called by simulation UL (89) 3

64 randomize called by simulation DL (87), 3simulation UL (89)

65 redraw frame panel called by permode event callback and 30AMC event callback handlersin wimax GUI (101), setup zones (84)

66 repcode event fcn called by repcode event callback handler 6in wimax GUI (101)

67 reset data regions called by mh2 callback handler 4in wimax GUI (101)

68 reset frame called by several event handlers 10in wimax GUI (101)

Table 3: Version 12 source files (P to R).



69 scpm dl fusc 128 called by gensubchan DL (47) 6




73 scpm dl pusc 128 called by gensubchan DL (47) 7




77 scpm ul pusc 128 called by gensubchan UL (48) 7




81 setup DL data regions called by frame panel event callback 25handler in wimax GUI (101)

82 setup results txt panels called by wimax GUI (101) 45

83 setup UL data regions called by frame panel event callback 74handler in wimax GUI (101)

84 setup zones called by frame panel event callback 17handler in wimax GUI (101)

85 show DL databurst called by mh2 callback handler 5in wimax GUI (101),process cntl click fcn (59),process dble click fcn (60)

86 show UL databurst called by mh2 callback handler 17in wimax GUI (101),process cntl click fcn (59),process dble click fcn (60)

87 simulation DL called by mh4 callback handler 127in wimax GUI (101)

88 simulation setup called by mh4 callback handler 7in wimax GUI (101)

89 simulation UL called by mh4 callback handler 38in wimax GUI (101)

90 SS CID event fcn called by SS CID event callback handler 4in wimax GUI (101)

91 SStoBS xmit wavefront called by wimax GUI (101) 6

92 symbol params called by simulation DL (87) 3

Table 4: Version 12 source files (S).



93 uiuc event fcn called by UIUC event callback handler 4in wimax GUI (101)

94 UL PUSC map LUT called by simulation UL (89) 4

95 update DLMAP msg called by several event handlers 10in wimax GUI (101)

96 update permutations called by frame panel event callback 8handler in wimax GUI (101)

97 update sim mod type called by results msg panel callback 7handler in wimax GUI (101),simulation setup (88),simulation UL (89)

98 update subchannels called by permode event callback and 5AMC event callback handlersin wimax GUI (101)

99 update zone panel fcn called by permode event callback and 39AMC event callback handlersin wimax GUI (101),delete DL zone (19),delete UL zone (20)

100 viterbi called by simulation DL (87), simulation UL (89) 4

101 wimax GUI - main program - 284

Table 5: Version 12 source files (U to W).


4.2 Software architecture

Figure 12 shows a simplified diagram of the simulation software architecture.

Figure 12: Simulation block diagram

The simulation is launched by executing the wimax GUI program. The program first definesand creates the various GUI components, such as the display panel, control panels, droplist widgets, pushbuttons, etc. This is illustrated by the thick black arrow in Figure 12.Pointers to various GUI objects are stored in the global data section. The global datasection allows all external functions to have access to these GUI objects.

The next section of the wimax GUI program contains the various event handlers. The GUIobjects contain pointers to event handlers that are called when a certain action occurs, suchas when the mouse button is clicked inside a widget or a pushbutton is pressed. This isillustrated by the thick brown arrow in Figure 12. The wimax GUI program contains atotal of 39 event handlers.


Event handlers are short sections of code that call external functions. This is illustratedby the blue lines in Figure 12. The external functions perform the bulk of the processing,then update the GUI (illustrated by the thick green arrow) and/or modify global variables(illustrated by the red lines). There are a total of 100 external functions, 2 of which arecurrently unused.

Two external functions are worthy of special mention here; simulation DL and simula-tion UL. When the Simulation->Run button is pressed in the GUI, it is vectored to themh4 callback event handler. This event handler calls simulation DL, then simulation UL,thereby executing a single DL and a single UL simulation run.

The last section of the wimax GUI program contains the global data section. This sectioncontains pointers to the various GUI objects and global variables. External functions sharedata by reading and writing global variables. This is illustrated by the red lines in Figure12.


5 WiMAX simulation example

This section contains a complete, detailed WiMAX simulation example on how to configureand run the simulation program. The complete output listing generated by the program isincluded.

5.1 Scenario definition

Before launching wimax GUI it is helpful to first define the simulation scenario on paper.In this example suppose we want to setup the simulation as shown in Figure 13.

The BS will transmit a total of 6 data bursts to the SS’s as shown. SS #1 will receive burst#3, SS #3 will receive burst #1, etc. Note that there is no DL burst for SS #2. Burst #6is a broadcast message sent to all SS’s. Each DL burst has a modulation type and codingrate associated. The minimum UBS required for each burst is shown in bytes. Bursts #1and #3 will use FUSC subchannel permutation while bursts #2, #4, #5 and #6 will usePUSC subchannel permutation.

On the uplink, SS’s transmit data bursts as shown to the BS. SS #1 has two bursts allocated;burst #2 and burst #3. SS #2 will transmit burst #4, SS #3 will transmit burst #1, etc.Note that SS #4 does not have a UL burst assigned.

Each UL burst has a modulation type and coding rate associated. The minimum UBSrequired for each burst is shown in bytes. All UL bursts will use PUSC subchannel permu-tation.

Each SS will be assigned CIDs as shown in Figure 13.

5.2 Waveform setup

Once the simulation scenario has been defined, execute the wimax GUI program. Theprogram automatically enters the waveform setup mode. As the nominal bandwidth, cyclicprefix, frame duration and DL/UL subframe ratio used in this example are default programvalues (i.e. 10-MHz, 1/8, 5-msec, and 54%), no changes are necessary to the waveformsetup.

Select Setup->DL/UL zones in the top-level menu and designate a FUSC permutation zonein the DL subframe. The FUSC zone is for DL bursts #1 and #3 shown in Figure 14.

5.3 DL/UL data bursts setup

Use the hypothetical scenario defined in Figure 13. Select Setup->DL data bursts in thetop-level menu. Assign each DL data burst by clicking and dragging the pointer. Set theDL burst parameters using the LHS control panel.


Figure 13: Example simulation scenario

Figure 14: Example zone setup


When the DL data bursts setup is complete, select Setup->UL data bursts in the top-level menu. Assign each UL data burst by clicking on a slot boundary. Set the UL burstparameters using the LHS control panel.

The completed waveform should be similar to that shown in Figure 15.

Figure 15: Example data bursts setup

5.4 Simulation setup

Use the hypothetical scenario defined in Figure 13. Select Simulation->Setup in the top-level menu. Use the AUTO pushbutton to automatically assign default CIDs to each SS.Assign the SUI channel number to each cell sector, then click on the cell sector to generatea random instance of the channel. The corresponding channel properties will be displayedin the LHS simulation panel. Set the SNR for each cell segment. The final simulation setupshould be similar to the one shown in Figure 16.

5.5 Running the simulation

To run the simulation, select Simulation->Run in the top-level menu. The simulation willperform a single DL cycle followed by a single UL cycle. Status messages will be displayedin each cell sector as the simulation executes. It is normal for an SS to encounter errorsduring any part of the simulation. The following errors may occur on the DL due to acombination of a degraded channel, burst modulation used and channel noise:

1. FFT size and CP could not be determined,2. Number of symbols received could not be determined,3. Channel estimate error,


Figure 16: Example simulation configuration

4. Cell IDs could not be extracted from preamble,5. FCH extraction error,6. DL-MAP extraction error,7. DL-MAP decoding error,8. UL-MAP extraction error,9. UL-MAP decoding error.

On any of these 9 error conditions the SS drops the DL frame as further processing wouldresult in more errors.

Allow the simulation to run to completion. At the end of the simulation the DL and ULBER results may be inspected by clicking on the simulation results panel at the bottom.The detailed simulation steps can be inspected by scrolling down in the simulation statusmessage panel.

The following is a complete listing generated by the program for the example of Figure 13.Some of the key program steps are noted in text boxes.


STARTING DOWNLINK SIMULATION..DL MAP length: 14-slotsApplying FEC and modulating DL MAP message..

UL MAP length: 7-slotsApplying FEC and modulating UL MAP message..

Creating mapping matrices..matrix for zone 1 [30 x 21] (PUSC)matrix for zone 2 [16 x 8] (FUSC)

Filling mapping matrices..Data burst: 1 -> zone 2 matrix (FUSC)Data burst: 2 -> zone 1 matrix (PUSC)Data burst: 3 -> zone 2 matrix (FUSC)Data burst: 4 -> zone 1 matrix (PUSC)Data burst: 5 -> zone 1 matrix (PUSC)Data burst: 6 -> zone 1 matrix (PUSC)

The program generates random data that will be transmitted on each DL burst.These values are compared to those received by each SS to generate the bit-error rates.

Generating random data for each burst..Data burst: 1 UBS: 108-bytes

Tx data 1: 0x32C0D29F7E71..Data burst: 2 UBS: 432-bytes

Tx data 2: 0x99FE8DE59294..Data burst: 3 UBS: 108-bytes

Tx data 3: 0x924CCA28986A..Data burst: 4 UBS: 324-bytes

Tx data 4: 0x9B523AAF0FA8..Data burst: 5 UBS: 216-bytes

Tx data 5: 0xCFBEDA2CA6F2..Data burst: 6 UBS: 84-bytes

Tx data 6: 0x646371ADA894..

FEC, or forward error correction are the steps of randomization, convolutional codingand interleaving applied to the data bursts.

Applying FEC and modulating data for each burst..Data burst: 1

DIUC: 0 (QPSK(CC)1/2)Ncpc: 2 code rate: 1/2 mod type: 2

Data burst: 2DIUC: 3 (16QAM(CC)3/4)Ncpc: 4 code rate: 3/4 mod type: 3




Data burst: 6DIUC: 0 (QPSK(CC)1/2)Ncpc: 2 code rate: 1/2 mod type: 2

Generating DL subframe matrix..Generating preamble for DL subframe..

IDCell(0): 0 IDCell(1): 0 IDCell(2): 0NFFT: 1024Boost: 9 dB

Mapping preamble to DL subframe..Generating frame control header (FCH)..Applying FEC and modulating FCH..


Mapping FCH to DL subframe..Mapping DL MAP to DL subframe..Mapping UL MAP to DL subframe..Mapping databursts to DL subframe..

Burst 1.. FUSCBurst 2.. PUSCBurst 3.. FUSCBurst 4.. PUSCBurst 5.. PUSCBurst 6.. PUSC

Generating channel for BS to SS#1SUI: 1 reset cnt: 82 fltr delay: 0






This point represents the end of the processing performed by the BS as it transmitsthe frame through the communications channels to the SS’s.

Transmitting DL subframe..

Start of SS #1 DL processing.

SS #1 (CID 0xAAAA) processing receive buffer..Determining FFT size and CP..

NFFT: 1024 CP: 1/8 symbol length: 115225 symbols received in DL subframe..Removing CP and applying FFT to received signal..Performing preamble-based channel estimation..

phase correction: 0Extracting cell IDs from preamble..

segment: 0 IDCell: 0segment: 1 IDCell: 0segment: 2 IDCell: 0

Extracting FCH..Demodulating and restoring FCH..

used subchan bitmap: 1 1 1 1 1 1repetition code: 0 0coding type: 0 0 0DL MAP length: 14 slots

Extracting DL MAP..Demodulating and restoring DL MAP..

DL MAP message length: 672-bits (84-bytes)Decoding DL MAP..DIUC: 3

Data burst #2 16QAM(CC)3/4Number of CIDs assigned: 1CID: 0xEEEE

DIUC: 4Data burst 64QAM(CC)1/2Number of CIDs assigned: 1CID: 0xDDDD

DIUC: 6Data burst #5 64QAM(CC)3/4Number of CIDs assigned: 1CID: 0xFFFF

DIUC: 0


Data burst #6 QPSK(CC)1/2Number of CIDs assigned: 6

The CID of SS #1 is 0xAAAA. The SS correctly identifies that DL data burst #6(a broadcast burst) is assigned to it.

CID: 0xAAAA (match)CID: 0xBBBBCID: 0xCCCCCID: 0xDDDDCID: 0xEEEECID: 0xFFFF

DIUC: 15IE type: STC Zone Switch IEzone offset: 17 (symbols)SCPM: FUSC

DIUC: 0Data burst #1 QPSK(CC)1/2Number of CIDs assigned: 1CID: 0xCCCC

DIUC: 2Data burst #3 16QAM(CC)1/2Number of CIDs assigned: 1

The CID of SS #1 is 0xAAAA. The SS correctly identifies that DL data burst #3is assigned to it.

CID: 0xAAAA (match)Extracting UL MAP..Demodulating and restoring UL MAP..

UL MAP message length: 336-bits (42-bytes)Decoding UL MAP..UIUC: 1

Data burst #1CID: 0xCCCC

UIUC: 5Data burst #2

The CID of SS #1 is 0xAAAA. The SS correctly identifies that UL data bursts #2and #3 are assigned to it.

CID: 0xAAAA (match)UIUC: 3

Data burst #3CID: 0xAAAA (match)

UIUC: 1Data burst #4CID: 0xBBBB

UIUC: 4Data burst #5CID: 0xEEEE

UIUC: 5Data burst #6CID: 0xFFFF

Processing DL data burst(s)..data burst #6

DL zone: 1SCPM type: 1modulation: QPSK(CC)1/2code rate: 1/2coding bits: 2repetition code: 0boosting: 0

data burst #3DL zone: 2


SCPM type: 2modulation: 16-QAM(CC)1/2code rate: 1/2coding bits: 4repetition code: 0boosting: 0

Extracting data burst(s)..Data burst #6 SCPM: PUSCData burst #3 SCPM: FUSC

Demodulating and restoring data burst(s)..Data burst #6

Rx data: (84-bytes) 0x646371ADA894..BER: 0.00 %

Data burst #3Rx data: (108-bytes) 0x924CCA28986A..BER: 0.00 %

SS #1 DL processing completed..


SS #2 (CID 0xBBBB) processing receive buffer..Determining FFT size and CP..









DIUC: 4Data burst #4 64QAM(CC)1/2Number of CIDs assigned: 1CID: 0xDDDD


DIUC: 0Data burst #6 QPSK(CC)1/2Number of CIDs assigned: 6CID: 0xAAAA

The CID of SS #2 is 0xBBBB. The SS correctly identifies that DL data burst #6(a broadcast burst) is assigned to it.

CID: 0xBBBB (match)CID: 0xCCCCCID: 0xDDDD


CID: 0xEEEECID: 0xFFFF



DIUC: 2Data burst #3 16QAM(CC)1/2Number of CIDs assigned: 1CID: 0xAAAA

Extracting UL MAP..Demodulating and restoring UL MAP..



UIUC: 5Data burst #2CID: 0xAAAA

UIUC: 3 Data burst #3CID: 0xAAAA

UIUC: 1Data burst #4

The CID of SS #2 is 0xBBBB. The SS correctly identifies that UL data burst #4is assigned to it.

CID: 0xBBBB (match)UIUC: 4

Data burst #5CID: 0xEEEE




Extracting data burst(s)..Data burst #6 SCPM: PUSC





SS #3 (CID 0xCCCC) processing receive buffer..Determining FFT size and CP..












DIUC: 0Data burst #6 QPSK(CC)1/2Number of CIDs assigned: 6CID: 0xAAAACID: 0xBBBB

The CID of SS #3 is 0xCCCC. The SS correctly identifies that DL data burst #6(a broadcast burst) is assigned to it.

CID: 0xCCCC (match)CID: 0xDDDDCID: 0xEEEECID: 0xFFFF

DIUC: 15IE type: STC Zone Switch IE zone offset: 17 (symbols)SCPM: FUSC

DIUC: 0Data burst #1 QPSK(CC)1/2Number of CIDs assigned: 1

The CID of SS #3 is 0xCCCC. The SS correctly identifies that DL data burst #1is assigned to it.

CID: 0xCCCC (match)DIUC: 2

Data burst #3 16QAM(CC)1/2Number of CIDs assigned: 1CID: 0xAAAA



Data burst #1

The CID of SS #3 is 0xCCCC. The SS correctly identifies that UL data burst #1is assigned to it.


CID: 0xCCCC (match)UIUC: 5

Data burst #2CID: 0xAAAA







data burst #1DL zone: 2SCPM type: 2modulation: QPSK(CC)1/2code rate: 1/2coding bits: 2repetition code: 0boosting: 0

Extracting data burst(s)..Data burst #6 SCPM: PUSCData burst #1 SCPM: FUSC



Data burst #1Rx data: (108-bytes) 0x32C0D29F7E71..BER: 0.46 %



SS #4 (CID 0xDDDD) processing receive buffer..Determining FFT size and CP..











The CID of SS #4 is 0xDDDD. The SS correctly identifies that DL data burst #4is assigned to it.

CID: 0xDDDD (match)DIUC: 6

Data burst #5 64QAM(CC)3/4Number of CIDs assigned: 1CID: 0xFFFF

DIUC: 0Data burst #6 QPSK(CC)1/2Number of CIDs assigned: 6CID: 0xAAAACID: 0xBBBBCID: 0xCCCC

The CID of SS #4 is 0xDDDD. The SS correctly identifies that DL data burst #6(a broadcast burst) is assigned to it.

CID: 0xDDDD (match)CID: 0xEEEECID: 0xFFFF



DIUC: 2Data burst #3 16QAM(CC)1/2Number of CIDs assigned: 1CID: 0xAAAA


UL MAP message length: 336-bits (42-bytes)Decoding UL MAP..

The CID of SS #4 is 0xDDDD. The SS correctly identifies that none of theUL data bursts are assigned to it.

UIUC: 1Data burst #1CID: 0xCCCC







Since there are no UL bursts assigned to SS #4 it will not perform any UL processing.

No data burst in UL subframe for SS #4Processing DL data burst(s)..

data burst #4DL zone: 1SCPM type: 1modulation: 64-QAM(CC)1/2code rate: 1/2coding bits: 6repetition code: 0boosting: 0


Extracting data burst(s)..Data burst #4 SCPM: PUSCData burst #6 SCPM: PUSC


Rx data: (324-bytes) 0x9B523AAF0FA8..BER: 0.00 %

Data burst #6Rx data: (84-bytes) 0x646371ADA894..BER: 0.00 %



SS #5 (CID 0xEEEE) processing receive buffer..Determining FFT size and CP..


phase correction: 0.99482Extracting cell IDs from preamble..


Extracting FCH..Applying phase correction..

Demodulating and restoring FCH..used subchan bitmap: 0 0 0 0 0 0repetition code: 1 1coding type: 1 1 1DL MAP length: 241 slots

*** SIMULATION ERROR: incorrect FCH ***Extracting DL MAP..

SS #5 is unable to extract the DL-MAP, hence it drops the frame.No further processing is performed.


Could not extract DL MAP..


SS #6 (CID 0xFFFF) processing receive buffer..Determining FFT size and CP..


phase correction: 0.83774Extracting cell IDs from preamble..









The CID of SS #6 is 0xFFFF. The SS correctly identifies that DL data burst #5is assigned to it.

CID: 0xFFFF (match)DIUC: 0

Data burst #6 QPSK(CC)1/2Number of CIDs assigned: 6CID: 0xAAAACID: 0xBBBBCID: 0xCCCCCID: 0xDDDDCID: 0xEEEE

The CID of SS #6 is 0xFFFF. The SS correctly identifies that DL data burst #6(a broadcast burst) is assigned to it.

CID: 0xFFFF (match)DIUC: 15

IE type: STC Zone Switch IEzone offset: 17 (symbols)SCPM: FUSC


DIUC: 2Data burst #3 16QAM(CC)1/2


Number of CIDs assigned: 1CID: 0xAAAA








UIUC: 5Data burst #6CID: 0xFFFF (match)

The CID of SS #6 is 0xFFFF. The SS correctly identifies that UL data burst #6is assigned to it.


DL zone: 1SCPM type: 1modulation: 64-QAM(CC)3/4code rate: 3/4coding bits: 6repetition code: 0boosting: 0


Extracting data burst(s)..Data burst #5 SCPM: PUSCData burst #6 SCPM: PUSC


Rx data: (216-bytes) 0xCFBEDA2CA6F2..BER: 0.23 %

Data burst #6Rx data: (84-bytes) 0x646371ADA894..BER: 0.00 %


End of DL processing part. In the UL processing part, each SS transmits to the BSin the data bursts allocated to it.


STARTING UPLINK SIMULATION..

Start of SS #1 UL processing.The SS transmits to the BS on UL bursts #2 and #3.

SS #1 (CID 0xAAAA) processing UL..

Number of burst(s) assigned: 2

Burst #2 - UIUC: 5 (64QAM(CC)1/2) repcode: 0

UBS: 108-bytes

Generating random data for burst #2..

Tx data 2: 0x51B0A83C0CA1..

Applying FEC and modulating data..


UBS: 60-bytes


Tx data 3: 0xA56D53C8B3A7..


Generating UL subframe matrix..

Mapping databurst(s) to UL subframe..

Transmitting UL subframe..

Start of SS #2 UL processing.The SS transmits to the BS on UL burst #4.

SS #2 (CID 0xBBBB) processing UL..


Burst #4 - UIUC: 1 (QPSK(CC)1/2) repcode: 0

UBS: 84-bytes


Tx data 4: 0x246846577DDA..






SS #3 (CID 0xCCCC) processing UL..


Burst #1 - UIUC: 1 (QPSK(CC)1/2) repcode: 0

UBS: 132-bytes


Tx data 1: 0x83BFB6C1BCB4..






SS #4 does not have any UL bursts assigned hence it does not transmit to the BS.

SS #4 (CID 0xDDDD) processing UL..

No UL burst(s) assigned..

SS #5 encountered an error during the DL-MAP processing,hence it does not transmit to the BS.

SS #5 (CID 0xEEEE) aborting UL processing..

DL-MAP extract error.


SS #6 (CID 0xFFFF) processing UL..



UBS: 144-bytes


Tx data 6: 0x60E824ABCFEF..





Base station processing receive buffer..

Removing CP and applying FFT to received signal..

The BS processes the UL-subframe containing all data bursts received.Since the BS originally defined the burst locations, the originating SS’sand burst parameters are known.

Processing burst #1 from SS #3 (CID 0xCCCC)

Modulation: QPSK(CC)1/2

Code rate: 1/2

Ncpc: 2

Repetition code: 0

Demodulating and restoring data burst..

Rx data: (132-bytes) 0x83BFB6C1BCB4..

BER: 0.38 %

UL burst #1 processing completed.

Processing burst #2 from SS #1 (CID 0xAAAA)

Modulation: 64-QAM(CC)1/2

Code rate: 1/2

Ncpc: 6

Repetition code: 0



Rx data: (108-bytes) 0x51B0A83C0CA1..

BER: 0.00 %


Processing burst #3 from SS #1 (CID 0xAAAA)


Code rate: 1/2

Ncpc: 4

Repetition code: 0


Rx data: (60-bytes) 0xA56D53C8B3A7..

BER: 0.00 %


Processing burst #4 from SS #2 (CID 0xBBBB)

Modulation: QPSK(CC)1/2

Code rate: 1/2

Ncpc: 2

Repetition code: 0


Rx data: (84-bytes) 0x246846577DDA..

BER: 0.00 %


Processing burst #6 from SS #6 (CID 0xFFFF)


Code rate: 1/2

Ncpc: 6

Repetition code: 0


Rx data: (144-bytes) 0x60E824ABCFEF..

BER: 0.35 %


>>


6 Conclusion

Version 12 (V12) of the physical layer mobile WiMAX network simulation environmentsoftware models the complete downlink and uplink processes of a mobile WiMAX system.The program contains the core functionalities specified by the IEEE802.16e-2005 standard.The simulation is GUI-based, enabling quick and easy specification of any type of WiMAXwaveform. The GUI also allows specification of the communications channel propertiesbetween the base station and the subscriber stations.

The V12 simulation version is a developmental version. Not all of the parameters that canbe specified by the GUI are actually used by the simulation. These parameters will beimplemented in future software versions:

1. Currently only PUSC and FUSC subcarrier permutation modes can be specified in theDL subframe. AMC permutation zones can be specified using the GUI but will not beprocessed. Future versions of the software will implement all DL zone switches, such asAMC, OFUSC, and TUSC, as specified by the WiMAX standard.

2. Currently only PUSC subcarrier permutation mode can be specified in the UL subframe.AMC and OPUSC permutation zones can be specified using the GUI but will notbe processed. Future versions of the software will implement all UL zone switches,as specified by the WiMAX standard.

3. Frame segmentation.

4. Data burst repetition and boosting.

5. Transmit data types. All transmit data defaults to random data, although image andvoice data types can be specified using the GUI.

6. Adaptive modulation and coding. AMC has not been implemented although AMC zonescan be specified by the GUI.

7. Channel quality channels, CDMA ranging and PAPR reduction channels have not beenimplemented.

8. UL subframe block-type allocations.

9. Handling of all DIUC and UIUC data types.

10. MAC layer management messages.

11. Interface of I/Q data to external test equipment.


References

[1] Jeffrey G. Andrews, Rias Muhamed, Arunabha Ghosh (2007), Fundamentals ofWiMAX - Understanding Broadband Wireless Networking, Prentice Hall.

[2] Byeong Gi Lee, Sunghyun Choi (2008), Broadband Wireless Access and LocalNetworks: Mobile WiMAX and WiFi, Artech House.

[3] IEEE (2004), IEEE Standard for Local and Metropolitan Area Networks,Number IEEE Std 802.16-2004 in Part 16: Air Interface for Fixed Broadband WirelessAccess Systems, IEEE, 3 Park Avenue, New York, NY 10016-5997, USA: IEEEComputer Society and the IEEE Microwave Theory and Techniques Society.

[4] IEEE (2006), IEEE Standard for Local and Metropolitan Area Networks,Number IEEE Std 802.16e-2005 and IEEE Std 802.16-2004/Cor1-2005 in Part 16: AirInterface for Fixed Broadband Wireless Access Systems Amendment 2: Physical andMedium Access Control Layers for Combined Fixed and Mobile Operation in LicensedBands and Corrigendum 1, IEEE, 3 Park Avenue, New York, NY 10016-5997, USA:IEEE Computer Society and the IEEE Microwave Theory and Techniques Society.

[5] IEEE (2001), Channel Models for Fixed Wireless Applications, Number IEEE802.16.3c-01/29r4, IEEE, IEEE 802.16 Broadband Wireless Access Working Group.

[6] Cai, Xiaodong and Giannakis, Georgios B. (2004), Error Probability Minimizing Pilotsfor OFDM with M-PSK Modulation over Rayleigh Fading Channels, IEEETransactions on Vehicular Technology, 53(1), 146–155.


List of acronyms

AMC Adaptive Modulation and CodingARP Advanced Research ProjectAST Allocation Start TimeBER Bit Error RateBPSK Binary Phase Shift KeyingBS Base StationBSID Base Station IdentificationBTC Binary Turbo CodingBW BandwidthCC Convolutional CodingCDMA Code Division Multiple AccessCID Connection IdentificationCP Cyclic PrefixDCD Downlink Channel DescriptorDIUC Downlik Interval Usage CodeDL DownlinkFCH Frame Control HeaderFFT Fast Fourier TransformFUSC Full Usage of Sub-CarriersGUI Graphical User InterfaceHLL Higher Level LayerID IdentificationIE Information ElementIEEE Institute of Electrical and Electronics EngineersIFFT Inverse Fast Fourier TransformLHS Left Hand SideLMB Left Mouse ButtonMAC Media Access ControlMCEW Modern Communications Electronic WarfareMCP Main Control PanelMS Mobile StationOFDMA Orthogonal Frequency Division Multiple AccessOFUSC Optional Full Usage of Sub-CarriersOPUSC Optional Partial Usage of Sub-CarriersPAPR Peak-to-AVerage Power RatioPHY PhysicalPN Pseudo Noise (or Pseudonoise)PS Physical SlotPUSC Partial Usage of Sub-CarriersQAM Quadrature Amplitude ModulationQPSK Quaternary Phase Shift KeyingRHS Right Hand SideRMB Right Mouse Button


RTG Receiver Turnaround GapSCPM Sub-Carrier Permutation ModeSNR Signal-to-Noise RatioSS Subscriber StationSUI Stanford University InterimTTG Transmitter Turnaround GapTUSC Tiled Usage of Sub-CarriersUBS Uncoded Block SizeUCD Uplink Channel DescriptorUIUC Uplink Interval Usage CodeUL UplinkWiMAX Worldwide Interoperability for Microwave Access




DOCUMENT CONTROL DATA(Security classification of title, body of abstract and indexing annotation must be entered when document is classified)

1. ORIGINATOR (The name and address of the organization preparing thedocument. Organizations for whom the document was prepared, e.g. Centresponsoring a contractor’s report, or tasking agency, are entered in section 8.)

nEW Technologies Inc.300 March Road, Suite 406, Kanata, Ontario, K2K2E2

2. SECURITY CLASSIFICATION (Overallsecurity classification of the documentincluding special warning terms if applicable.)

UNCLASSIFIED

3. TITLE (The complete document title as indicated on the title page. Its classification should be indicated by the appropriateabbreviation (S, C or U) in parentheses after the title.)

Design and development of a physical layer mobile WiMAX network simulation environment

4. AUTHORS (Last name, followed by initials – ranks, titles, etc. not to be used.)

Szeker, B.

5. DATE OF PUBLICATION (Month and year of publication ofdocument.)

January 2010

6a. NO. OF PAGES (Totalcontaining information.Include Annexes,Appendices, etc.)

68

6b. NO. OF REFS (Totalcited in document.)

6

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Contract Report

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Defence R&D Canada – Ottawa3701 Carling Avenue, Ottawa, Ontario, Canada K1A 0Z4

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15dg02

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W7714-050965/001/TOR

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10b. OTHER DOCUMENT NO(s). (Any other numbers which maybe assigned this document either by the originator or by thesponsor.)

DRDC Ottawa CR 2009-239

11. DOCUMENT AVAILABILITY (Any limitations on further dissemination of the document, other than those imposed by securityclassification.)( X ) Unlimited distribution( ) Defence departments and defence contractors; further distribution only as approved( ) Defence departments and Canadian defence contractors; further distribution only as approved( ) Government departments and agencies; further distribution only as approved( ) Defence departments; further distribution only as approved( ) Other (please specify):

12. DOCUMENT ANNOUNCEMENT (Any limitation to the bibliographic announcement of this document. This will normally correspondto the Document Availability (11). However, where further distribution (beyond the audience specified in (11)) is possible, a widerannouncement audience may be selected.)

Unlimited

13. ABSTRACT (A brief and factual summary of the document. It may also appear elsewhere in the body of the document itself. It is highlydesirable that the abstract of classified documents be unclassified. Each paragraph of the abstract shall begin with an indication of thesecurity classification of the information in the paragraph (unless the document itself is unclassified) represented as (S), (C), (R), or (U).It is not necessary to include here abstracts in both official languages unless the text is bilingual.)

This report details and summarizes the work performed in developing a computer simulationenvironment of the physical layer of a mobile WiMAX network. Since the work of WiMAX mod-eling was first started in April of 2008, several developmental computer simulation models werecreated of increasing complexity, the results of which were published in a prior report. The knowl-edge gained through these earlier simulation efforts were incorporated into the current simulationenvironment version.

The amount of effort required to unravel the complexities of WiMAX was considerable but hasproduced an advanced simulation environment that is in accordance with the IEEE802.16e-2005standard. The current version of the simulation environment refines the models previously de-veloped with the addition of new functionalities and a Graphical User Interface (GUI) to facilitatethe entry of the simulation parameters.

The computer simulation described in this report models both the physical layer and part of themedia access layer of a WiMAX network. The report describes the software architecture toprovide a better understanding of its components and includes detailed instructions on how tosetup and run the simulation.

14. KEYWORDS, DESCRIPTORS or IDENTIFIERS (Technically meaningful terms or short phrases that characterize a document and couldbe helpful in cataloguing the document. They should be selected so that no security classification is required. Identifiers, such asequipment model designation, trade name, military project code name, geographic location may also be included. If possible keywordsshould be selected from a published thesaurus. e.g. Thesaurus of Engineering and Scientific Terms (TEST) and that thesaurus identified.If it is not possible to select indexing terms which are Unclassified, the classification of each should be indicated as with the title.)

WiMAX802.16e-2005WirelessDigitalCommunicationsSimulationsMatlab

Design and development of a physical layer mobile WiMAX ...

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