Browsing by Author "Guo, Yile"

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    Performance evaluation of an optical code-division multiplexing system with four-wave mixing effect
    (1996) Guo, Yile; Young, James F.
    The performance of an optical code-division multiplexing (CDM) system using spectral encoding and bipolar codes under the influence of four-wave mixing (FWM) is evaluated in terms of error probability. In the CDM system the first order crosstalk due to four-wave mixing can be cancelled using antisymmetric mask patterns in the encoders and decoders. The second order FWM crosstalk is proportional to the number of users supported by the system. For a CDM system using an ideal broadband source, shot noise is the major factor that causes error in the lower signal power range, while four-wave mixing crosstalk dominates in the higher signal power range. The CDM system has a lower error probability in the higher signal power range than the WDM system, i.e., the performance of the CDM system is better than that of the WDM system.
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    Resource Allocation in Wireless CDMA Multimedia Networks
    (1999-05-20) Guo, Yile; Center for Multimedia Communications (http://cmc.rice.edu/)
    In this thesis we developed a resource allocation framework for wireless code division multiple access (CDMA) networks that support multi-class traffic with different data rates and bit error rate requirements. We proposed a new resource allocation scheme using joint adaptive power control and antenna array multiuser receiver in multipath fading system. In this scheme both transmit power and receiver filter adapt to time- varying fading channel state. By dynamically assigning users appropriate transmit power and receiver filter, the scheme can guarantee users' diverse quality of service (QoS) requirements and significantly improve quality and capacity of the system. We derived theory for abstraction of bandwidth resource and characterization of system capacity for multi-class traffic in multipath fading system. Bandwidth resource allocated to a user can be abstracted as "effective bandwidth", determined by the user's source data rate and target bit error rate. Capacity inmultipath fading system can be characterized by a theoretical bound. Simulations show that actual system capacity in multipath fading environment is close to the theoretical bound at large power constraint. The multirate multiuser receiver can achieve significantly larger capacity for users with higher source data rate and lower target bit error rate than conventional matched-filter receiver. The antenna array multiuser receiver can provide large capacity for users with higher signal-to-interference ratio requirement and achieve high bandwidth utility at lower power constraints. We also proposed a new call admission control scheme for CDMA cellular system that incorporates adaptive power control and antenna array multiuser receiver and supports multi-class traffic. The scheme is based on estimation of othercell interferenceand implemented distributively in each cell. The scheme can adapt to various traffic distribution. Capacity determined by the admission control agrees well with the actual system capacity in the simulation. The scheme can achieve high bandwidth utilization and guarantee QoS requirements of all the users.
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    Resource allocation in wireless CDMA multimedia networks
    (1999) Guo, Yile; Aazhang, Behnaam
    In this thesis we developed a resource allocation framework for wireless code division multiple access (CDMA) networks that support multi-class traffic with different data rates and bit error rate requirements. We proposed a new resource allocation scheme using joint adaptive power control and antenna array multiuser receiver in multipath fading system. In this scheme both transmit power and receiver filter adapt to time-varying fading channel state. By dynamically assigning users appropriate transmit power and receiver filter, the scheme can guarantee users' diverse quality of service (QoS) requirements and significantly improve quality and capacity of the system. We derived theory for abstraction of bandwidth resource and characterization of system capacity for multi-class traffic in multipath fading system. Bandwidth resource allocated to a user can be abstracted as "effective bandwidth", determined by the user's source data rate and target bit error rate. Capacity in multipath fading system can be characterized by a theoretical bound. Simulations show that actual system capacity in multipath fading environment is close to the theoretical bound at large power constraint. The multirate multiuser receiver can achieve significantly larger capacity for users with higher source data rate and lower target bit error rate than conventional matched-filter receiver. The antenna array multiuser receiver can provide large capacity for users with higher signal-to-interference ratio requirement and achieve high bandwidth utility at lower power constraints. We also proposed a new call admission control scheme for CDMA cellular system that incorporates adaptive power control and antenna array multiuser receiver and supports multi-class traffic. The scheme is based on estimation of other cell interference and implemented distributively in each cell. The scheme can adapt to various traffic distribution. Capacity determined by the admission control agrees well with the actual system capacity in the simulation. The scheme can achieve high bandwidth utilization and guarantee QoS requirements of all the users.