THESIS
1997
xi, 112 leaves : ill. ; 30 cm
Abstract
Second generation digital wireless communication systems enable the transmission of different kinds of services, such as voice and data transmission. The general public is aware of the benefits of wireless communications, and demand more advanced forms of services such as multimedia services. Of the various multi-access techniques, Code Division Multiple Access (CDMA) has been regarded as an important part of the third generation Personal Communication Systems (PCS) because of its high frequency utilization and suitability for handling multimedia communication. A multimedia system is expected to facilitate high quality transmission in the form of voice, data, image and video. In order to achieve high quality multimedia services, reliable transmission is required. Therefore, a sophistica...[
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Second generation digital wireless communication systems enable the transmission of different kinds of services, such as voice and data transmission. The general public is aware of the benefits of wireless communications, and demand more advanced forms of services such as multimedia services. Of the various multi-access techniques, Code Division Multiple Access (CDMA) has been regarded as an important part of the third generation Personal Communication Systems (PCS) because of its high frequency utilization and suitability for handling multimedia communication. A multimedia system is expected to facilitate high quality transmission in the form of voice, data, image and video. In order to achieve high quality multimedia services, reliable transmission is required. Therefore, a sophisticated Forward Error Correction (FEC) system is needed to provide wireless multimedia services.
In this thesis, we investigate the use of FEC as well as concatenated coding in asynchronous DS/CDMA communications over frequency selective Rayleigh fading channels. The Chernoff bound and Union bound for both coding schemes are derived, and the tightness of these bounds is investigated using computer simulations. In particular, we analyze the average bit error rate (BER) performance and capacity tradeoffs between various system parameters under a fixed total bandwidth expansion and concatenated codes constraint requirements. Some effective coding parameter combinations which affect the system design will be presented. In addition, the throughput performance for both systems is presented under average signal-to-noise ratio/fixed total bandwidth expansion and fixed processing gain constraints.
Owing to the fact that a multimedia system is required to support services with different rates and Quality of Services (QoS), different error control schemes are used to satisfy the requirements of different media. We perform the capacity analysis of a wireless multimedia DS/CDMA system based on error control and optimal power control over multipath Rayleigh fading links. The error control schemes consist of FEC, diversity and Automatic Repeat reQuest (ARQ). The concatenated codes with a Reed-Solomon outer code and a convolutional inner code are used as FEC. The effect of imperfection in the power control algorithm on the capacity of the proposed system is also investigated.
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