Adaptive power control for multi-antenna and cooperative communications with imperfect channel knowledge

• Main Author: Zhang, Xiao Juan
• Other Authors: Gong Yi
• Format: Theses and Dissertations
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Power electronics
• Online Access: https://hdl.handle.net/10356/40924
• Institution: Nanyang Technological University

In this thesis, we consider adaptive power control for multi-antenna and cooperative fading channels with imperfect channel state information (CSI). The thesis comprises two main parts. In the first part, we study temporal power control in multi-antenna and cooperative relaying channels subject to long-term power constraints at the transmitters, with a focus on the asymptotically high signal-to noise ratios (SNRs). Efficient power control schemes based on noisy CSI at the transmitters (CSIT) and/or receivers (CSIR) are proposed to maximize the achievable diversity-multiplexing tradeoff (DMT). We also provide a framework to systematically study the achievable DMT in multi-input multi-output (MIMO) and cooperative systems with noisy CSI. We firstly consider a MIMO system and develop novel two way training strategies to improve the DMT. To make more efficient use of the imperfect CSI, joint power and rate control schemes are proposed which drastically increase the achievable DMT, especially at high multiplexing gains. Next, we extend the DMT analysis to cooperative relaying channels. Both conventional amplify-and-forward (AF)/decode and-forward (DF) and dynamic DF (DDF)relaying protocols are considered. We show that long-term power control based on imperfect CSIT significantly improves the DMT of the conventional AF and DF relaying protocols. Moreover, it is shown that the DDF relaying, which supports higher spectral efficiencies, also enjoys a further improved DMT over the conventional relaying protocols. In the second part, we study spatial power control in cooperative relaying channels to minimize the system outage/error probability. In particular, we consider adaptive power allocation (PA) among the source and relay(s) subject to a short-term sum power constraint at the source and relay(s). We first consider a dual-hop DF relay system with multiple antennas at the destination. With partial CSIT in the form of channel statistics, we take both PA and relay location into joint optimization. Secondly, we consider a multi-hop DF relay system with imperfect CSIT, where the imperfect CSIT is due to limited channel feedback from the destination to the source and relays.