Mobile WiMAX Tech Measurement Workshop• WiMAX Forum: An industry organization to promote the IEEE 802.16 standard for Broadband Wireless Access (BWA) • Has established a series
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
WiMAX 802.16 OFDMA (802.16e)• Mobile wireless broadband • Application: Provide Mobile
Wireless broadband to devices, such as PDA’s, computer, cell phones.
UWB• High-speed cable replacement• Application: Wireless USB
Home Theater, video streaming, portable devices
Agilent Restricted
Mobility
802.11/802.16
(Roam Between Service Areas)
Consolidate 802.16/802.16a/ 802.16c Modifications and Interoperability
2-11 GHz
Non Line of Sight
Up to 75 Mbps
(20 MHz Chan)
802.16
System profiles
Interoperability
10-66 GHz
Line of Sight
Up to 134 Mbps (28 MHz Chan)
Fixed Wireless
IEEE 802.16e
(802.16-2005)
IEEE 802.16d
(802.16-2004)
Rev. 5
IEEE 802.16a
January 2003
IEEE 802.16c
December 2002
IEEE 802.16
December 2001
IEEE 802.16 WirelessMAN Evolution
4
Agilent Restricted
What are WiMAX and 802.16? (I)• IEEE 802.16: An IEEE sponsored specification targeted at a
variety of Broadband Wireless Access opportunities not addressed by others like 802.11 (WLAN). Below is the IEEE802.16 document structure specific to 802.16e:
Agilent Restricted
802.16 standards802.16-2004 (Released)
802.16e related standards
802.16e MobileBWA < 6 GHz 512 to 2048 FFT
OFDMA w/64 QAM 5, 10, 20 MHz
Air Interface Application Frequency Modulation Bandwidth /Max bit rate
WirelessMAN - SC Line of Sight, Pt-Pt Microwave 10-66 GHz Single Carrier
w/64 QAM20 -28 MHz /134.4 Mbps
WirelessMAN - SCa NLOS,Fixed BWA < 11 GHz Single Carrier
• WiBro (Wireless Broadband) - began a few years ago as a proprietary TTA standard for Korea, formerly called HPI (High-speed Portable Internet)
• Now mostly merged into 802.16e standard as one of the system profiles• 1024 sub-carriers in 8.75 MHz BW in 2.3-2.4 GHz band only• Development is more advanced than 802.16e: tested at speeds up to 120
km/hr• Commercial service expected to be launched in April 2006
6
Agilent Restricted
Agenda
• Overview for Broadband Wireless Access• WiMAX-OFDMA Technologies• WiMAX-OFDMA Signal Meas. & Analysis• 802.16e WiMAX-OFDMA RF Measurement• Resource
Data NFCH Data 1 Data 2Chan est. . . .Preamble Payload
1 sym N sym N sym N sym 1 sym
Long synch
1 sym
Payload – multi-symbol, multi-mod type, no overlap
Agilent Restricted
Contrasting OFDMs--802.11a vs. 802.16 WiMAX
802.11a 52 carriers,312.5 kHzspacing
802.16 200 carriers,
90 kHzspacing .
.
.
200 carriers,6.7 kHzspacing
802.11a (18 MHz)
802.16 (1.5 MHz)
4 BPSK Pilots
8 BPSK Pilots
802.16 (20 MHz)
BPSK, QPSK, 16QAM, 64QAM
BPSK, QPSK, 16QAM, 64QAM
.
.:
10 MHz7.0 MHz3.5 MHz
:A smaller sub-carrier spacing gives greater immunity to multipath fading
8
Agilent Restricted
Contrasting OFDMs – 802.16e WiMax Mobile
83-120 Pilots
802.16e: Freq range: 2- 6 GHz Data rate: ≤ 70Mbps Mobile/Fixed: Mobile (60~100kph)
FFT: 2048Carriers: 1680Spacing: ~11kHz
FFT: 1024Carriers: 840Spacing: ~11kHz
FFT: 512Carriers: 408Spacing: ~11kHz
42-60 Pilots
802.16e (5 MHz)
166-240 BPSK Pilots, variable
location
802.16e (20 MHz)
QPSK, 16QAM, 64QAM
OFDMA Symbol Number
time
802.16e (10 MHz)
Payload – multi-symbol, multi-mod type, overlap
Agilent Restricted
802.16 OFDMA Concepts: SlotsIn OFDMA, the minimum possible data unit is a “Slot”A slot has 2 dimensions, one dimension is time, the other is subchannel number3 most common slot sizes
•1 Subchannel and 1 OFDMA Symbol•1 Subchannel and 2 OFDMA Symbols•1 Subchannel and 3 OFDMA Symbols
Different “Zones” will use different slot sizes
1 subchannel SLOT
1 subchannel
1 subchannel
Symbol 1Symbol 2Symbol 3
SLOT
SLOT
9
Agilent Restricted
802.16e OFDMA ConceptsSub-channelization – Sharing the bandwidth
• The carriers are organized into “logical sub-channels” consisting of ~28 subcarriers each.
• MAC layer assigns user data to 1 or more logical sub-channels for enough symbol times to carry the required no. of bits.
34 logical sub-channels,
24.7 carriers/sub-channel (10MHz)
• Subchannel-to-subcarrier assignment changes for every symbol, based on permutation formula seeded by variables such as Cell-ID, sector number, etc.
802.16 OFDMA ConceptsExample of a ‘data burst’ allocated to a user
0123456789
k k+1 k+ 2 k+3 k+4 k+5 k+6
n+6 n+7 n+8
n n+1 n+2n+3 n+4 n+5
• A data burst is a group of contiguous sub channels and symbols
• The base station assigns a data burst/region to a user to use to receive or transmit data.
LogicalSubchannels
perm
utat
ion
Physical Subcarriers
Symbol number
10
Agilent Restricted
802.16 OFDMA Concepts: ZonesThere are currently more than 7 zones that have been defined
PUSC (partial usage of subchannels)
FUSC (full usage of subchannels)
PUSC with all subchannels
Optional FUSC
AAS (Adaptive Antenna System)
AMC (Adaptive Modulation and Coding)
Option FUSC with all subchannels
Zones are used to help implement basestation functionality such as beamforming, assigning subchannels to different sectors of a single cell, and to define subchannelization that reduces basestation to basestation interference
• Coding: CC only mandatory one• Two basic types of preambles:
Long and Short• All carriers have same
modulation in one symbol• Sub-channelization optional• Space Time Coding (STC)
optional
• OFDMA with 128, 512, 1024, or 2048 carriers in 1.25, 5, 10, or 20 MHz BW respectively. Some requests for additional BWs for European market. • Coding: CC mandatory; CTC and STC optional but popular (CTC required for WiBro)• Many preambles, with 114 preamble modulation series based on segment and IDCell
• New features:• Permutation zones: PUSC, FUSC,
OPUSC, AMC, OFUSC, TUSC1, TUSC2• Bursts and zones allocated by sub-
channels and symbols• Sub-channels divided into segments
(BTS sectors)• Physical sub-channels renumbered to
logical sub-channels• Hybrid automatic repeat request (HARQ)• Adaptive antenna system (AAS) for
beamforming• Repetition coding• Power boosting
This is just a partial list. 802.16e is MUCH more complex than the 256-carrier OFDM PHY!
Fixed WiMAX (OFDM)802.16e OFDMA
11
Agilent Restricted
802.16 OFDMA ConceptsDrawing of ‘data region’ or ‘data bursts’
• In OFDMA, data bursts overlap in time
• Maximizes data flow in complex environment
OFDMA
OFDM
• In 802.16-2004 OFDM user data DO NOT overlap in time.
• Option B7N(3G Application): Extends Option AYA Vector Modulation Analysis capabilities to include W-CDMA (3GPP),cdma2000, cdma20001xEV-DO and TD-SCDMA vector modulation analysis.
• Option B7R(WLAN Application): Vector Modulation Analysis capabilities for WLAN DSSS/CCK/PBCC/OFDM Signal.(89607 WLAN Test Suite license is included inside)
Pilot Tracking• In OFDMA, Pilots Change Location and are Not Present for All
Symbols
• In OFDMA, Pilot Tracking can “Break” Demod
• Demod relative to incorrect (data) carriers
• Demodulation Is Adjusted During A Subframe
• Demod is Performed Relative to the BPSK Pilots
• Some Errors are “Tracked Out” as Demod Follows Pilots
• Tracking Types can be Enabled/Disabled Independently
• Amplitude (default is off)
• Phase (default is on)
• Timing (default is off)
• Pilot Tracking Reduces Close-In Phase Noise
OFDMA
Agilent Restricted
Advanced Demodulation Results
• Common Pilot Error
• Pilot carriers provide continuous amplitude & phase reference to receiver
• Difference between the measured and ideal pilot subcarrier symbols
• Reveals signal changes during burst
OFDMA
33
Agilent Restricted
• Channel Frequency & Impulse Response. Derived From Preamble or Preamble + Data
Channel Response from Equalizer OFDMA
Agilent Restricted
Relative Subcarrier Power• New Data Type: Channel Frequency Response Adjacent
Difference• Adjacent subcarrier power difference
• Measured from preamble, every 3rd physical subcarrier, or from selected data, with interpolation
OFDMA
34
Agilent Restricted
Agenda
• Overview for Broadband Wireless Access• WiMAX-OFDMA Technologies• WiMAX-OFDMA Signal Meas. & Analysis• 802.16e WiMAX-OFDMA RF Measurement• Resource
Mobile WiMAX 802.16e RF Measurement
35
Agilent Restricted
WiMAX & Mobile WiMAX Transmitter Testing
Base-band Stduio
Digital Interface
RF/Analog BB VSA/89601A SW
Analog I/Q
Digital I/Q
89601A-B7S WiMAX
89601A-B7Y Mobile WiMAX
RFTx
Agilent Restricted
IEEE 802.16e OFDMA Tx Specifications Overview
8.4.12.1 – Transmit power level control8.4.12.2 – Transmitter Spectral Flatness8.4.12.3 – Transmitter Constellation Error (RCE)8.4.14.1 – Center Frequency and Symbol Clock Frequency Tolerance
36
Agilent Restricted
8.4.12 Transmitter requirements
• 8.4.12.1 Transmit power level control• The transmitter shall support monotonic
power level control of 45dB minimum (30 dB for license-exempt bands)
• To ensure that the receiver SNR does not degrade more than 0.5 dB due to the transmitter SNR, the relative constellation RMS error, averaged over subcarriers, OFDMA frames, and packets, shall not exceed a burst profile dependent value according to Table
-26-2664-QAM-1/2
-30-28
-24-20.5-18-15
Relative constellation error for SS (dB)
–30–28
–24–20–18–15
Relative constellation error for BS(dB)
Burst Type
64-QAM-3/464-QAM-2/3
16-QAM-3/416-QAM-1/2QPSK-3/4QPSK-1/2
38
Agilent Restricted
8.4.14 Frequency control• 8.4.14.1 Center Frequency and symbol clock frequency tolerance• For BS
• The transmitted center frequency, receive center frequency, and the symbol clock frequency shall be derived from the same reference oscillator.
• The reference frequency accuracy shall be better than ±2*10–6.• For SS
• Both the transmitted center frequency and the sampling frequencyshall be derived from the same reference oscillator.
• The center frequency shall deviate no more than 2% of the subcarrier spacing.
Agilent Restricted
IEEE 802.16e OFDMA Rx Specifications Overview
8.3.13.1.1 – Receiver Sensitivity8.3.13.1.2 – MS uplink transmit time tracking accuracy8.3.13.1.3 – MS aotonomous neighbor cell scanning8.3.13.2 – Receiver Adjacent and Non-adjacent channel Rejection8.3.13.3 – Receiver Maximum Input Signal8.3.13.4 – Receiver Maximum Tolerable Signal
39
Agilent Restricted
Agilent’s WiMAX Receiver Test BER/PER Testing
Rx
E4438C ESG Vector Signal Generator
Chipset Vendor-supplied SW will perform BER/PER
testing
WiMAX Signal Studio Software
Agilent Restricted
DUT
Digital I/Q or IF Signal Generation:Signal Generators with Digital Outputs
• Pre-Configured and Proprietary Signals using Arbitrary Waveform Generator