Space-time diversity versus feedback-based channel adaptation in cross-layer design of wireless networks

In order to support the quality of service (QoS) for data applications in wideband CDMA (W-CDMA) networks, space-time (ST) techniques are developed at the physical layer. The employment of such techniques also plays an important role in cross-layer design for wireless networks. In this paper, we investigate three different channel-feedback adaptation-based space-time systems, including non-adaptive, fast-adaptive, and slow-adaptive schemes. Our analysis reveals the tradeoff between the space-time diversity and channel-feedback adaptation. The improvement of QoS for data transmission can be achieved either by enhancing the space-time diversity or by increasing the channel-feedback. However, the space-time diversity impacts the system throughput more significantly than the channel-feedback adaptation. We also obtain a set of optimal system parameters to achieve the maximum throughput. Both numerical and simulation results show that the enhancement of space-time diversity can increase the system throughput and simplify the higher-layer protocol design using channel-feedback. Also compared are the throughput improvements as taking the feedback cost into account