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KI/ERA/GG/TKN Michael Lesan Approved Checked Date Rev Reference
Faith Tanui/Theo Makokha 2012-02-04
1.1.3 Time Needed
Approximately four hours including introduction but excluding exercises (the time schedule given is excluding exercises. Three hours are left for exercises and ending the course. This time can be allocated after each module, or used in the beginning of each day, or in some other way)
1.1.4 Reference Literature
WCDMA for UMTS: Radio Access for Third Generation Mobile
Communications, edited by: Harri Holma and Antti Toskala, ISBN: 0-471-
72051-8
1.1.5 Necessary Tools
Overhead projector, whiteboard and markers in different colours (and a PC
(running Excel and/or Matlab) and projector)
1.2 Module Guide
This module deals briefly with the evolution from 2G and 3G and many details of the CDMA transmitter.
It is likely that some of the course participants are fairly familiar with different types of coding and interleaving (since these are general concepts applicable to GSM and TDMA as well) so this part can probably be treated briefly. However, it can still be very instructive to show the Viterbi decoder in action by using an available spreadsheet, where the influence of noise can be seen quite clearly.
Most important is the discussion of PN codes (used to separate different
radiation sources) and orthogonal codes (used to separate different channels from
the same radiation source). The different code properties must be
understood and it can be instructive to run the available Matlab programs where the
different correlation properties are clearly seen.
I/Q modulation is a central part of WCDMA technology and must therefore also be
treated with some care. Check out the exercises and make sure that the answers to the following questions are provided in the lecture
Why is vocoding used in mobile phones instead of PCM voice coding? Why
is CRC error checking used for voice communications?
What types of FEC (Forward Error Correction) are used in 2G and 3G
cellular phones?
Under what conditions do FEC methods work the best?
KI/ERA/GG/TKN Michael Lesan Approved Checked Date Rev Reference
Faith Tanui/Theo Makokha 2012-02-04
What method is used in all wireless systems to optimise FEC coder performance?
When is long interleaving used? When is short interleaving used?
What is the difference between a “bit”, a “symbol”, and a "chip"?
What is the result when a PN code is correlated with itself or with a different PN code?
What limits the number of spread spectrum users that can share the same
RF frequency?
What are the important differences between orthogonal codes and PN codes
What two codes must be combined to implement a cellular CDMA system?
What are PN codes used for? What are orthogonal codes used for?
When a very high data-rate user uses a very short-length orthogonal code, what is the impact on the overall code space? On the spread spectrum processing gain?
Why is I/Q modulation used instead of simple BPSK?
Why is a raised-cosine filter used prior to the I/Q modulator?
1.3 Exercise Guide
Use the exercise on orthogonal codes (exercise 6) when discussing
orthogonal codes to illustrate that it actually works. Let the course participants work in pairs and send a coded message to each other and decode the received message.
The other exercise (exercise 1) can be distributed after the lecture so the
course participants get a chance to digest what they have just been told and as a
repetition to consolidate their newly acquired knowledge.
1.4 Summary
This module deals briefly with the evolution from 2G and 3G and many details of the CDMA transmitter such as different data protection coding methods, different orthogonal and spread spectrum codes and different modulation and filtering techniques.
KI/ERA/GG/TKN Michael Lesan Approved Checked Date Rev Reference
Faith Tanui/Theo Makokha 2012-02-04
http://3gpp.ericsson.se/specs/spec.htm (this link leads to servers where the
latest releases of 3GPP specifications are found, so all references listed in
later modules must be updated on a regular basis from these servers)
2.1.5 Necessary Tools Overhead projector, whiteboard and markers in different colours.
2.2 Module Guide Power control is essential in a CDMA system and the course participants must therefore understand why different power controls procedures are required.
The RAKE receiver is one of the key components of CDMA systems and it is therefore important that the course participants grasp the concepts of it. The difference between the various types of handover can also be related to some extent to the use of the RAKE receiver. Check out the exercises and make sure that the answers to the following questions are provided in the lecture
Why is fast power control used in all CDMA systems? Is fast power control required on the downlink, the uplink, or both?
If fast power control is not required for the downlink (base station) transmission, why is it employed anyway in both cdma2000 and WCDMA?
Why is open-loop power control required in a CDMA system? How is open-loop power control implemented?
What is meant by outer-loop power control?
Why must a CDMA receiver use a RAKE receiver?
How does a RAKE receiver reduce multipath interference?
What is the "searcher" finger used for?
Why is soft handover essential in a cellular CDMA system?
What is the essential power control “rule” during soft handover?
Does soft handover increase overall system capacity?
KI/ERA/GG/TKN Michael Lesan Approved Checked Date Rev Reference
Faith Tanui/Theo Makokha 2012-02-04
2.3 Exercise Guide
Exercise 2 can be distributed after the lecture so the course participants get a change to digest what they have just been told and as a repetition to consolidate their newly acquired knowledge.
2.4 Summary This module treats the CDMA RAKE receiver, power control and soft/softer handover.
KI/ERA/GG/TKN Michael Lesan Approved Checked Date Rev Reference
Faith Tanui/Theo Makokha 2012-02-04
3.2 Module Guide
Although of course very interesting this part can sometimes be treated more briefly since other courses (WCDMA radio network design) discuss this in quite some detail.
Check out the exercises and make sure that the answers to the following
questions are provided in the lecture
What are typical reuse factors for analog and TDMA Systems?
Is frequency reuse of fundamental importance in CDMA? If not, then
where is reuse planning important for CDMA?
What are the theoretical limits of capacity for AMPS, IS-136, GSM, IS-95,
and WCDMA in terms of number of users per cell (or per sector of a
sectored cell)?
What is the practical capacity that has been observed in IS-95 CDMA
systems (users per sector)?
Why are these theoretical limits achievable in FDMA and TDMA systems,
but not in CDMA systems?
What fundamentally limits the uplink capacity of a cellular CDMA system?
What fundamentally limits the downlink capacity of a cellular CDMA system?
In practice, is cellular CDMA capacity limited more by the uplink or the
downlink?
Note that comparisons between CDMA, TDMA and GSM are notoriously difficult and be prepared for discussion, disagreement and arguments no matter how you approach this subject.
3.3 Exercise Guide
Exercise 3 can be distributed after the lecture so the course participants get a change
to digest what they have just been told and as a repetition to
consolidate their newly acquired knowledge.
3.4 Summary
This module treats capacity considerations of CDMA systems.
KI/ERA/GG/TKN Michael Lesan Approved Checked Date Rev Reference
Faith Tanui/Theo Makokha 2012-02-04
4.1.2 Learning Methods
Instructor-led lectures, student exercises and group work.
4.1.3 Time Needed
Approximately four hours (the time schedule given is excluding exercises.
Three hours are left for exercises and ending the course. This time can be
allocated after each module, or used in the beginning of each day, or in some other
way).
4.1.4 Reference Literature WCDMA for UMTS: Radio Access for Third Generation Mobile Communications, edited by: Harri Holma and Antti Toskala, ISBN: 0-471- 72051-8
3GPP TS 25.201-v310: Physical layer general description
3GPP TS 25.301-v350: Radio interface protocol architecture
3GPP TS 25.302-v350: Services provided by the physical layer
3GPP TS 25.211-v330: Physical channels and mapping of transport channels onto
physical channels (FDD)
3GPP TS 25.212-v330: Multiplexing and channel coding (FDD)
3GPP TS 25.213-v330: Spreading and modulation (FDD)
HPSK spreading for 3G, Application Note1335 from Agilent Technologies, at http://contact.tm.agilent.com/tmo/Notes/English/NotesSubjects.html
4.1.5 Necessary Tools
Overhead projector, whiteboard and markers in different colours.
4.2 Module Guide
This part is heavy but also the essence of this course (WCDMA air interface).
It may be confusing for the course participants that, to the logical and physical channels well known from GSM, transport channels are added. The WCDMA uplink and downlink wall charts are very useful to give an overview of what is going on. Probably not the same amount of time needs to be spent on all physical channels but certainly a few must be discussed in detail to gain some understanding of the underlying principles. In particular channels which support variable rates.
Check out the exercises and make sure that the answers to the following
KI/ERA/GG/TKN Michael Lesan Approved Checked Date Rev Reference
Faith Tanui/Theo Makokha 2012-02-04
What does the acronym “UTRAN” stand for?
What are the key components of the UTRAN?
List the full name and purpose of each of these WCDMA physical channels: CPICH, P-CCPCH, SCH, S-CCPCH, DPCCH/DPDCH, AICH, PICH, PRACH, PCPCH, PDSCH, CSICH, AP-AICH and CD/CA-ICH
What code is used to allow the UE to distinguish between BSs
What code is used to allow the UE to distinguish between data channels from one BS?
What code is used to allow the BS to distinguish between UEs
What code is used to allow the BS to distinguish between data channels from one UE?
What is the range of physical layer data rates available on the downlink
and uplink?
What is the range of payload data rates available on the downlink and uplink?
Describe the purpose of the following bits that are embedded in the DPCCH/DPDCH: Pilot, TPC and TFCI
What is the purpose of the first and second Interleavers?
What interleaving depth is used for voice? for layer 3 control data?
Why is complex spreading used in the uplink?
What is the main difference between complex spreading and HPSK?
4.3 Exercise Guide
Exercise 4 can be distributed after the lecture so the course participants get a change to digest what they have just been told and as a repetition to consolidate their newly acquired knowledge.
4.4 Summary
This module treats the WCDMA physical layer (for the FDD mode) in quite some
KI/ERA/GG/TKN Michael Lesan Approved Checked Date Rev Reference
Faith Tanui/Theo Makokha 2012-02-04
5 Module 5 WCDMA Acquisition, Synchronisation, and Handover
5.1 Preparation
Objectives of Module 5
After this module the course participants are able to:
1. Explain the mobile station acquisition - Base Station Cell Site Timing - Primary Synchronisation Code (SC1) - Secondary Synchronisation Code Group (SC2) -
Forward Link Scrambling Codes - Slot Synchronisation
- Frame Synchronisation
- Scrambling Code Group Determination
2. Explain the mobile station access
- Random Access
- Packet Channel Access
3. Explain the handover in a WCDMA system - Handover Scenarios - Soft Handover Procedures - Compressed Mode Hard Handover -
Handover to/from GSM
Objectives
5.1.1 Learning Material
OH 5/03813 - EN/LZU 108 5306 (slides 1 to 34)
Exercises 03814 - EN/LZU 108 5306
5.1.2 Learning Methods
Instructor-led lectures, student exercises and group work.
KI/ERA/GG/TKN Michael Lesan Approved Checked Date Rev Reference
Faith Tanui/Theo Makokha 2012-02-04
What makes the Packet Access channel different from the Random
Access and Dedicated Traffic Channels? What is the fundamental difference between IS-95/cdma2000 handover and WCDMA handover?
What is the fundamental problem with soft handover when BSs are not
precisely synchronised and how does WCDMA solve this problem?
5.3 Exercise Guide
Exercise 5 can be distributed after the lecture so the course participants get a change to digest what they have just been told and as a repetition to consolidate their newly acquired knowledge.
5.4 Summary
This module treats WCDMA operational procedures such as acquisition,