On The Physical Layer Performance Analysis And Optimization In Wireless Cooperative Networks

It has been proved that, the cooperative communication system can achieve higher di-versity gain with the help of relays under the normalized power and bandwidth. As a newspace diversity technology, cooperative system searches the idle network node to form thevirtual MIMO. On the other hand, for the multi-source, multi-destination cooperative mul-ticast network, applying the wireless network coding to the relays can also help to enhancenot only the diversity gain but also the network throughput. In the dissertation, we focus onsome key technologies in cooperative systems.Firstly, we analyze the throughput-reliability tradeoff (TRT) in one-source, one-destination and multi-relay system. TRT is a information rule proposed for MIMO systemwith the aim to reveal the relationship between transmission rate, outage probability andsignal-to-noise ratio (SNR). It raised the concept operating regions, within which, outageprobability curves under arbitrary transmission rate and SNR can be linearly approached.However, there is a open problem whether TRT can be applied to any other communicationsystems. To solve this problem, we setup the slotted amplify-and-forward (SAF) protocoland slotted decode-and-forward (SDF) protocol. Then a detailed TRT study is performedon the two protocols. We conclude that, though the TRT expression in cooperative systemremains the same as that in MIMO system, the definitions of operating regions are differ-ent in two systems. Simulations prove that the given TRT analysis accurately reveal therelationship between transmission rate, outage probability and SNR in the two protocols.Then we pay our attention to the two-source, two-destination and one-relay cooperativemulticast network. Three network coding protocols, i.e., non-regenerative network coding(NRNC) protocol, regenerative complex field network coding (RCNC) protocol and regener-ative Galois field network coding (RGNC) protocol are proposed and applied to the multicastnetwork to enhance the throughput. To make a effective and general comparison of the threeprotocol, we turn to another information rule, i.e., diversity-multiplexing tradeoff (DMT).By deducing the DMT of the three protocols, we conclude that, when multiplexing gain is small enough, the three protocols earn the same diversity gain. However, as the multiplexinggrowing, NRNC outperform the other two protocols by achieving higher diversity gain. TheDMT analysis also reveal that, under the same system performance, each network codingprotocol outperforms the traditional transmission scheme without network coding in term ofnetwork throughput. The power allocation schemes are put forward according to differentprotocols with the metric of system frame error probability (SFEP), where we consider twocases, i.e., with the statistical channel state information (CSI) and with the instant CSI.At last, we extend the multicast network with one relay to the scenario with arbitrarynumber of relays. The relays are arranged by round-robin way. A more general expressionsof SFEP in the three protocols are deduced. Through the SFEP, we find that each protocolcan not achieve the full diversity gain. So we introduce the precode design. For NRNC, wepropose the joint power allocation and precoder scheme. The precoder is designed accordingto whether the statistical CSI or instant CSI is available at sources. While for the other twonon-regenerative protocols, we also give the corresponding precode schemes. In addition,power allocation is also considered to get higher performance. Our analysis show that powerallocation in multi-relay multicast network help to achieve more coding gain. However, onlythrough precoding, we can achieve the more diversity gain.