Come Join Us!! COMMUNICATION STRATEGY FOR WIRELESS SYSTEMS WITH TRANSMIT AND PROCESSING POWER CONSTRAINT PhD Dissertation Defense Jialin He Advisor: Dr. Dinesh Rajan Southern Methodist University, Dallas, TX Monday, April 28, 2014 2:00 pm-3:00 pm Room 210, Junkins Building Abstract: The core challenge in wireless communications is to maximize the achievable date rate under the constraint of system resources. Traditional communication strategies are developed under the assumption that the transmit power is considered as the exclusive source of power consumption. However, the ignorance of processing power weakens the optimality of those communication strategies. In this dissertation, we analysis the change of the optimal transmission and channel state information (CSI) feedback scheme with the consideration of both transmit and processing power constraint in signal and multiple antenna systems. In single antenna systems, we consider a fading channel as shown in Figure 1.2. We first develop the optimal bursty transmission scheme when the transmitter has a perfect knowledge of CSI (CSIT). Then, in the scenario without CSIT, we derive the optimal quantization scheme which can achieve the maximum expected rate in two different scenarios. For systems with a short-term power constraint, we derive an algorithm to find the optimum quantization schemes with bursty transmission. For systems with a long-term power constraint, we prove that no explicit bursty transmission is required. We also propose a two-step power allocation method, based on the traditional waterfilling followed by a water adjustment step, which achieves the maximum expected rate. We quantify the gain that the proposed algorithms can achieve for different quantization levels. From the outage achievable rate perspective, we show that bursty transmission is beneficial and propose the transmission scheme for transmitter to maximize the outage achievable rate. In multiple antenna systems, we develop transmission schemes that maximize the spatial multiplexing rate. The proposed transmission strategy uses a combination of antenna selection with a bursty transmission strategy to achieve increased rate when complete channel state information is available at the transmitter. We also develop an algorithm, based on dynamic programming, to determine the optimal combinations of antenna configurations and their fractional transmission durations. For a MIMO system with partial CSIT, we design a feedback scheme, where the information of both the antenna configuration and the precoding matrix is sent to the transmitter. We also provide a heuristic method to design the codebook that sends back antenna configuration information to the transmitter. Numerical results indicate that significant improvements in rate are obtained with the proposed strategy over a traditional precoder feedback strategy. We further discuss the performance of bursty transmission using the metric of achievable rate-per-cost. We proposed a one-codeword coding scheme which outperforms both traditional and the bursty transmission in certain power constraint region. It is closer to the Verdus capacity-per-cost than the other two schemes. We also measure the processing power on real device to prove its existence. We find that the processing cost can take up more than 50% of the total power consumption of a wireless system.
Posted on: Fri, 25 Apr 2014 16:34:32 +0000
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