Simulation of Third Generation CDMA SystemsByFakhrul AlamABSTRACTThe goal for the next generation of mobile communications system is to seamlessly integrate a wide variety of communication services such as high speed data, video and multimedia traffic as well as voice signals. The technology needed to tackle the challenges to make these services available is popularly known as the Third Generation (3G) Cellular Systems. One of the most promising approaches to 3G is to combine a Wideband Code Division Multiple Access (WCDMA) air interface with the fixed network of Global System for Mobile communications (GSM). In this thesis a signal simulator was implemented according to the physical layer specification of the IMT-2000 WCDMA system. The data is transmitted in a frame by frame basis through a time varying channel. The transmitted signal is corrupted by multiple access interference which is generated in a structured way rather than treating it as Additive White Gaussian Noise (AWGN). The signal is further corrupted by AWGN at the front end of the receiver. Simple rake diversity combining is employed at the receiver. We investigate the bit error rate at both uplink and downlink for different channel conditions. Performance improvement due to error correction coding scheme is shown. The simulator developed can be an invaluable tool for investigating the design and implementation of WCDMA systems.Chapter 1IntroductionThe goal for the next generation of mobile communications system is to seamlessly provide a wide variety of communication services to anybody, anywhere, anytime. The intended service for next generation mobile phone users include services like transmitting high speed data, video and multimedia traffic as well as voice signals. The technology needed to tackle the challenges to make these services available is popularly known as the Third Generation (3G) Cellular Systems. The first generation systems are represented by the analog mobile systems designed to carry the voice application traffic. Their subsequent digital counterparts are known as second generation cellular systems. Third generation systems mark a significant leap, both in applications and capacity, from the current second generation standards. Whereas the current digital mobile phone systems are optimized for voice communications, 3G communicators are oriented towards multimedia message capability.1.1 First Generation Cellular SystemsThe first generation cellular systems generally employ analog Frequency Modulation(FM) techniques. The Advanced Mobile Phone System (AMPS) is the most notable of the first generation systems. AMPS was developed by the Bell Telephone System. It uses FM technology for voice transmission and digital signaling for control information. Other first generation systems include: Narrowband AMPS (NAMPS) Total Access Cellular System (TACS) Nordic Mobile Telephone System (NMT-900)All the first generation cellular systems employ Frequency Division Multiple Access(FDMA) with each channel assigned to a unique frequency band within a cluster of cells.1.2 Second Generation Cellular SystemsThe rapid growth in the number of subscribers and the proliferation of many incompatible first generation systems were the main reason behind the evolution towards second generation cellular systems. Second generation systems take the advantage of compression and coding techniques associated with digital technology. All the second generation systems employ digital modulation schemes. Multiple access techniques like Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA) are used along with FDMA in the second generation systems. Second generation cellular systems include: United States Digital Cellular (USDC) standards IS-54 and IS-136 Global System for Mobile communications (GSM) Pacific Digital Cellular (PDC) cdmaOne1.3 Third Generation Cellular SystemsThird generation cellular systems are being designed to support wideband services like high speed Internet access, video and high quality image transmission with the same quality as the fixed networks. The primary requirements of the next generation cellular systems are: Voice quality comparable to Public Switched Telephone Network (PSTN). Support of high data rate. The following table shows the data rate requirement ofthe 3G systemsTable 1.1: 3G Data Rate RequirementsMobility NeedsMinimum Data RateVehicular144 kbpsOutdoor to indoor and pedestrian384 kbpsIndoor Office2 Mbps Support of both packet-switched and circuit-switched data services. More efficient usage of the available radio spectrum Support of a wide variety of mobile equipment Backward Compatibility with pre-existing networks and flexible introduction ofnew services and technology An adaptive radio interface suited to the highly asymmetric nature of mostInternet communications: a much greater bandwidth for the d