CDMA Systems Engineering Principles
The What And Why Of The Design And Where It Is Going
Summary
This four-day course is designed for engineers and managers who wish to understand the system design of IS-95 CDMA cellular and PCS systems, the principles of its deployment and operation, and the evolution that the design is undergoing to meet third-generation "anytime, anywhere" wireless system objectives. These topics are addressed in the context of the basic theory and practice of cellular telephone systems and are related to the underlying theory in a tutorial manner using numerical examples.
Instructor
Dr. Leonard E. Miller is vice president for research at J. S. Lee Associates, Inc. in Rockville, MD, and is co-author of CDMA Systems Engineering Handbook (Artech, 1998). His experience includes 14 years in instrumentation and signal processing at the US Naval Surface Weapons Center and 21 years at JSLAI in the analysis of EW, ESM, and the survivability of tactical communications systems, including spread spectrum systems, as well as commercial wireless systems. Dr. Miller is a Senior Member of the IEEE and has EE degrees from Rensselaer Polytechnic Institute, Purdue University, and Catholic University. He has contributed over 50 papers to IEEE journals and conferences.
What You Will Learn
- What is the difference between spread spectrum and CDMA?
- What are the channelization, multiplexing, and synchronization schemes used in IS-95 and its derivatives?
- How do the forward and reverse RF link budgets compare with those for analog cellular systems?
- How are Walsh functions and PN codes generated and used in the system?
- What is the error performance of the modulation used in the system?
- How does the error-control coding affect the capacity?
- What is the Erlang capacity of a cellular system?
- How do the power control and soft handoff/diversity techniques enhance the caller capacity?
- How will the third-generation versions increase data rate and capacity?
Course Outline
- What is CDMA? Multiple access techniques: FDMA, TDMA, CDMA. Spread spectrum techniques. Second generation cellular objectives. Capacity improvement using TDMA (IS-54) and CDMA (IS-95). PCS frequency allocations.
- Basic Cellular Engineering. Telephone traffic theory. Erlang B statistics and trunking efficiency. Architecture of a mobile radio telephone system. Cellular concepts and tradeoffs: frequency-reuse, cell splitting, spectral efficiency. Cellular system link budgets. Hata and CCIR propagation models. Coverage vs. capacity. Hard vs. soft handoff, effect on link margins.
- Overview of IS-95 CDMA. Coordination of frequency and time. Use of GPS. Time alignment of PN codes. Base station pilot PN code offsets. Forward and reverse link channel parameters and operational features. Orthogonal multiplexing using Walsh functions. CDMA using PN codes. Open and closed loop power control. Interleaving techniques and their relationship to variable data rates. Soft handoff and diversity using Rake principle. Application to WLL, GlobalStar.
- Walsh Functions and PN Sequences. Properties of Walsh functions. Relation of Walsh and Hadamard functions. Generation of Walsh functions. Comparison of Walsh function use in forward and reverse links. Properties of PN sequences and their algebraic representation. Shift register implementation using masks. PN sequences in IS-95 and its derivatives.
- Modulation and Coding in IS-95. Correlation and spectral properties of binary waveforms. IS-95 spectral control requirements and FIR waveshaping. Error performances of forward and reverse link channel symbols. Frames and frame quality, CRC codes. Convolutional codes and their performance. Coding gains of convolutional codes.
- Diversity and Rake. Selection diversity and the improvements from it. Equal gain and maximal ratio combining and the improvements from them. The Rake concept and its use in IS-95.
- CDMA Cellular Engineering. Forward and reverse link co-channel interference. Re-use and cell loading parameters. Link budgets and forward/reverse link balancing. Link margins and reliability. Effects of power control and diversity on link margins. Model for CDMA call blocking. Erlang capacity of a CDMA system. CDMA coverage vs. capacity.
- CDMA Optimization Issues. Forward channel SNR requirements. Optimal allocation of forward link power. Fractions of power allocated to different Walsh channels. Selection of forward link fade margins. Limits on achievable margins. Asymptotic and power-limited forward link capacity.
- Third Generation CDMA Systems. IMT-2000 objectives, requirements, technologies. Overview of IS-95 evolution toward cdma2000. 1XRTT and 3XRTT. Major changes, IS-95 to IS-95A to IS-95B to IS-95C.
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