Research On The Multi-hop Data Relay Cellular-An Integrated Cellular And Ad-hoc Relay System Base On The Delay Estimation

Wireless data service is rapidly increasing nowadays. And the limited channel capacity has become a serious problem to the cellular wireless communication system.. Current strategy of channel allocation can be divided into two types: fixed channel allocation (FCA) and dynamic channel allocation.(DCA). With FCA, the channel-reuse pattern can be optimized and the management of channel assignment to a mobile terminal is simplified. However, such a scheme cannot accommodate fluctuating traffic in a cell: when the traffic increases, the packet delay may increase to a undesirable level, or even been blocked. To mitigate such a shortcoming, DCA schemes have been proposed, in which the pool of channels can be dynamically assigned to a cell depending on its current traffic level. However, such schemes generally requires complex and centralized control.In our work, we integrate the ad hoc networks into the cellular networks. We place a number of data relaying stations (DRSs) at strategic locations, which can be used to relay data packets between MHs and BTSs. By using multi-hop, some of the traffic can be diverted away from the hot cell, and to its neighboring cold cells, if one or more such cold neighbors exists, thereby achieving load balancing among the cells and increasing the cell capacity and system capacity. Such a scheme is called "Multi-hop Data Relay Cellular" (MDRC).Chapter 1 introduces the evolution of wireless communication technology, and the evolution of ad hoc networks. We also bring up the problem faced by current wireless communiction system.There is a detail description on cellular wireless commnunication system in Chapter 2. Here, we introduce the basic concept of cellular wireless commnunication system and system capacity. A series of techniques which aim to increase the system capacity and some arithmetic on channel allocation are introduced in chapter 2 too.Chapter 3 mainly about ad hoc networks. We introduce 3 aspects here: the characteristic of ad hoc networks, the channel access of ad hoc networks, and the creation and maintenance of the router of ad hoc networks.Chapter 4 presents the MDRC in detail. Firsly, the MDRC system model is described.The creation and maintenance of MDRC ad hoc router are introduced whereafter. And then, we focus on the strategy on how to decide which scheme mobile hosts should adopt to transmit the packets,which is based on the estimation of all kinds of delay. At last, we analyse the contribution the MDRC makes for load balance.Chapter 5 is the last one. Here, we introduce the processing flow of all kinds of nodes in MDRC. We also present the results of simulation, which can validate the improvement brought by MDRC.