Font Size: a A A

Transmission Techniques For MIMO System Under Imperfect CSI

Posted on:2017-01-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:Z J PengFull Text:PDF
GTID:1108330488457708Subject:Information and Communication Engineering
Abstract/Summary:PDF Full Text Request
With wide application of the mobile devices, we need high rate in the wireless networks, and the MIMO (multiple-input multiple-output) technique can satisfy this demand. The MIMO technique utilizes the space diversity to improve the spectral efficiency, and it needs channel state information (CSI). While, in some practical systems, especially in frequency division duplex (FDD) systems, we can not obtain perfect CSI. Hence, it is necessary to investigate the effect of imperfect CSI on the system performance of the MIMO systems. In this thesis, for the multiuser MIMO relay system, antenna selection MIMO system, and MIMO secrecy system, we study the system performance of these systems under imperfect CSI scenarios.In the second section of this thesis, we investigate the system performance of the multiuser MIMO relay system with imperfect CSI. In this amplify forward (AF) relay system, relay and users utilize channel estimation to estimate CSI, and then we adopt random vector quantization (RVQ) scheme to quantize the estimated CSI. We first derive the lower bound of the sum rate, and then utilize the lower bound to derive an upper bound of the rate loss for characterizing the effect of channel estimation error and quantization error on the system performance. Then, we utilize the upper bound to design the limited feedback strategy, and the rate loss can be controlled in a certain gap by employing the strategy. Moreover, we design an optimal pilot scheme by using the rate loss in high SNR region. At last, we also derive an upper bound of the sum rate.In the third section of this thesis, we study the system performance of the antenna selection MIMO system in the imperfect CSI. In this system, the receiver employs channel estimation technique to obtain estimated channel matrix and selects the antenna which has the best estimat-ed channel quality to make the reception. And we use RVQ scheme to quantize the estimated channel vector. Firstly, for the scenario existing only quantization error, we derive the closed expressions of outage probability and average symbol error rate (SER), and we derive a closed expression for the approximation of average capacity. Then, for the scenario with channel es-timation error and quantization error, by using the derived results for the above scenarios, we derive the closed expressions of outage probability, average SER, and the approximation of av-erage capacity. At last, we utilize the simulation results to verify our derived results for the above two scenarios, and the simulation results verify that the closed expression of the approximation for the average capacity can well approximate the average capacity.In the forth section and fifth section of this thesis, under imperfect CSI scenario, we re- spectively investigate the system performance of the MISOSE (multiple-input, single-output, single-eavesdropper) system and the MIMOME (multiple-input, multiple-output, multiple-eavesdroppers) system. For the two systems, the legitimate receiver employs channel estimation technique to estimate the channel vector and the channel matrix. Then, for the MISOSE system, we utilize RVQ scheme to quantize the estimated channel vector; while for the MIMOME sys-tem, we utilize random matrix quantization (RMQ) scheme to quantize the estimated channel matrix. For the MISOSE system and MIMOME system, the forth section and the fifth section of this thesis respectively derive the corresponding upper bounds of the secrecy rate loss to char-acterize the effect of imperfect CSI on the secrecy systems. And, we utilize the upper bounds to respectively design the corresponding limited feedback schemes for the two secrecy systems.’ For the two secrecy systems, the secrecy rate loss can be controlled in a certain gap by employ-ing the corresponding limited feedback schemes. Moreover, for the MIMOME system, we also derive the upper bound of the secrecy rate.
Keywords/Search Tags:MIMO, channel estimation, limited feedback, relay, physical layer security technique, antenna selection
PDF Full Text Request
Related items