Table of Contents

1 Introduction..

1.1 Why Wireless?.

1.1.1 Types of Transmission Mediums.

1.1.2 Advantages of Wireless Communication Systems.

1.1.3 Low & High Frequencies.

1.1.4 CDMA Modulation Techniques.

1.1.5 Effects in Radio Communication.

1.1.5.1 Path Loss.

1.1.5.2 Signal Attenuation.

1.1.5.3 Signal Fading.

1.2 Wireless Challenges.

1.2.1 Multiple Access Techniques.

1.2.1.1 FDMA.

1.2.1.2 TDMA.

1.2.1.3 TDMA vs. CDMA.

1.2.1.4 CDMA and TDMA Trends.

1.2.1.5 CDMA.

1.2.1.6 Advantages of Multiple Accesses.

1.2.1.7 Coverage Area.

1.2.1.7.1 Line Configuration.

1.2.1.7.2 Ring Configuration.

1.2.1.7.3 Star Configuration.

1.3 CDMA Principles.

1.3.1 FHSS (Frequency Hopping Spread Spectrum)

1.3.2 DSSS (Direct Sequence Spread Spectrum)

1.3.3 Advantages of Spread Spectrum..

1.3.3.1 Reduced Crosstalk Interference.

1.3.3.2 Better Voice Quality/Data Integrity and Less Static Noise.

1.3.3.3 Lowered Susceptibility to Multipath Fading.

1.3.3.4 Inherent Security.

1.3.3.5 Co-Existence.

1.3.3.6 Longer Operating Distances.

1.3.3.7 Hard to Detect

1.3.3.8 Hard to Intercept or Demodulate.

1.3.3.9 Harder to Jam..

1.4 CDMA Advantages.

1.5 CDMA and GSM Networks.

1.5.1 Advantages of CDMA over Other Systems.

1.6 CDMA History.

1.7 OFDM...

1.7.1 The General Usage of OFDM

2 CDMA Discrimination Codes.

2.1 Walsh Code.

2.1.1 Overview..

2.1.2 Walsh Code Creation.

2.2 Short Code.

2.3 Long Code.

2.4 Rake Receiver.

3 Power control.

3.1 Why Power Control?.

3.2 CDMA Power Control.

3.2.1 Reverse Open Loop Power Control

3.2.2 Reverse Closed Loop Power Control

3.2.3 Reverse Outer Loop Power Control

3.2.4 Forward Traffic Channel Power Control

4 4G new standards.

4.1 Objectives of the Fourth Generation.

4.2 The Shift from 3G toward 4G..

4.3 Spread Spectrum as a 4G Standard.

4.4 OFDMA as 4G Standard.

4.5 802.11n as 4G Standard.

4.6 802.16 As 4G Standard.

4.6.1 WiMAX Applications.

4.6.2 How WiMAX Works.

4.6.3 WiMAX Modulation Schemes.

4.6.3.1 Scalable OFDMA (SOFDMA)

4.6.3.2 Turbo coding.

4.6.3.3 Low density Party Check.

4.6.4 Adaptive Antenna Systems (AAS)

5 The future of CDMA and spread spectrum...

5.1 What is the CDMA Replacement?.

6 The Future of Mobile Vendors.

6.1 Meeting Market Growth.

6.2 Wireless Systems Future.

6.3 Increased Competition in the New Standards.

7 References.

Table of Figures

Figure 1 - Signal Reflection and Fading.

Figure 2 - FDMA Power, Frequency and Time.

Figure 3 - FDMA Frequency Response.

Figure 4 - TDMA Time Frame.

Figure 5 - TDMA Power, Frequency and Time.

Figure 6 - CDMA Power, Frequency and Time.

Figure 7 - Multiple Access Management System..

Figure 10 - Frequency Hopping in CDMA..

Figure 11 - Desired Signal Hope in CDMA..

Figure 12 - Transmitter Interference.

Figure 13 - OFDM Wireless LAN Receiver.

Figure 14 - Mobile Unit Transmitter.

Figure 15 - How WiMAX Works.