Research On Multiple Packet Reception Based On Successive Interference Cancellation In The Wireless Local Area Network

Over the past few years, along with the rapid development of wireless broadband access technology and the rapid spread of wireless terminal devices, wireless local area network (WLAN) has gradually become the necessities of life. People are no longer satisfied with traditional low-rate business and instead want to get high-throughput, high-bandwidth multimedia services, but the traditional wireless LAN has become increasingly powerless. Therefore, IEEE802.11 working group gradually accelerates the development of new protocol standard. From the initial 802.11b that supports 11Mbps to 802.11g which supports 54Mbps, until to 802.11n products which are commonly used now, the theoretical rate of up to hundreds of megabytes. However, the wireless LAN still can’t do well in solving the problems of multi-user interference and low channel utilization problems.In traditional 802.11 WLAN, each receiving node can only receive a single packet at a given time, which called single packet reception. When multiple packets are transmitted at the same channel from different users simultaneously, then the mutual interference produced by other users, that might prevent the correct decoding of the packet. In response to this situation, this thesis proposes a scheme that adopts multiple packet reception technology (MPR) in WLAN physical layer, allowing multiple users to use the same channel to transmit data simultaneously, and then Successive Interference Cancellation (SIC) can be used to decode the packets reliably at the receiving end. So, the limitation of the traditional single packet transmission in wireless local area network can be relaxed, even eliminated. Consequently an increase in the system throughput is expected and hidden terminals can be eliminated completely. In order to coordinate the implementation of the physical layer of the MPR, this thesis proposes a novel MAC protocol that with moderate modifications on the current MAC protocol.First of all, this thesis introduces the background of WLAN and research status of multiple packet reception, as well as multi-user detection theory of the physical layer in multiple packet reception system. Then describes the challenges which the multiple packet reception system faces in the WLAN, and multiple packet reception matrix model. In this section we focus on the principle of successive interference cancellation technology, as well as its advantages and disadvantages.Secondly, in the third chapter of the thesis, we present the overall implementation of multiple packet reception in the WLAN. Starting from the physical layer model, we also analyze the signal processing technology which called successive interference cancellation. Because the performance of multiple packet reception is closely related to differences of strength of the received signal in the receiving end, this paper describes methods of channel estimation in the WLAN, and control scheme of user power are given at the same time. In addition, the traditional access mechanisms of the MAC layer cannot match multiple packet reception scheme of the physical layer, therefore, we have to do moderate modifications on the current MAC protocol.Finally, this thesis briefly describes a simulation platform-according to the multiple packet reception scheme proposed in previously parts. At the end of this thesis, numerical simulation analyses about MPR illustrate the potential of the SIC-based multiple packet reception scheme, but it also faces some challenges.