Optimal Multi-user Resource Allocation for Distributed Antenna Systems

Future wireless networks are expected to support a wide variety of communication services such as voice, data and multimedia. However, there are two unique challenges brought by the wireless environment: the time-varying nature of the channel and the scarcity of the radio resources. In-depth investigation is therefore merited to see how to efficiently allocate the limited resources to meet diverse quality-of-service (QoS) requirements and maximize the utilization of available bandwidth based on the channel states of users.The distributed antenna system (DAS) has emerged as a promising candidate for the future beyond-3G or 4G systems thanks to its enormous capacity gains and flexible resource management. In DASs, many remote antenna ports are distributed over a large area and connected to a central processor by fiber, coax cable or microwave link. The distributed characteristic of antennas provides a much more efficient utilization of spatial resources; however, it also significantly complicates the channel modeling and system analysis. The optimal resource allocation of DAS in the single-user scenario has been thoroughly studied, i.e., how to assign the transmission phases, rate and power of different distributed antennas to a specific user. Nevertheless, the optimal multi-user resource allocation remains largely unknown.In this project, the resource allocation issue of DAS will be investigated in the multi-user scenario. The major tasks of the project include: - Investigating the optimal multi-user scheduling scheme for DASs. The researchers expect to prove that DASs can achieve a much higher sum capacity than the traditional cellular systems when Channel State Information (CSI) is available at the transmitter side. The optimal multi-user scheduler can be proposed based on the capacity analysis; - Formulating the general resource allocation framework for DASs. The researchers expect to demonstrate that in DASs, the optimal resource allocation problem can be decoupled using a network decomposition methodology; - Developing distributed algorithms to realize the optimal multi-user resource allocation in a large scale network with a reasonable complexity level and - Evaluating the performance of the proposed schemes in a practical environment with the effects of feedback error and delay included. Extensive performance comparisons with current cellular systems will be conducted to illustrate the performance gains achieved by DASs.