IDMA Design Of Iterative Detection

Multiple-Access is one of the key technologies in wireless communication area. There are three main Multiple-Access techniques, FDMA(Frequency Division Multiple-Access), TDMA(Time Division Multiple-Access) and CDMA( Code Division Multiple-Access). All these techniques can be used solely or mixed with one another. The purpose of these techniques is to get much more Multiple-Access competence within the limited Time-Frequence source.Interleave-Division Multiple Access(IDMA) is proposed by Prof. Li Ping coming from City University of Hong Kong. It originates from CDMA, hence many advantages are inherited from CDMA, in particular, diversity against fading and mitigation of the worst-case other-cell user interference problem. Verdu and shamai's research indicates that when a lot of users communicate simultaneously, the lower code rate is used, the better performance can be got which is closed to the theory Shannon limitation. Camparing to CDMA, IDMA gets rid of the special spread sequence and uses random interleavers to separate different users. It uses low rate code which can combine coding and spreading efficiently. At the user end, IDMA adopts a very simple chip-by-chip iterative TURBO MUD strategy. The normalized MUD cost (per user) is independent on the number of users.The use of iterative detection can improves system performance greatly, but on the other hand, the number of iteration is one of the bottlenecks of IDMA. Under situations where high communication speed is required, the detection time could be too long to be accepted. Also as more iteration numbers are used, the more consumption on resources are needed. These weaknesses can greatly limit the use of IDMA.In this paper, we aim to settle the problems proposed above without performance sacrifice. The main works are listed bellow:1. Analyze the information updating process during interative detection from the point of math theory. From the viewpoint of posterior probability, this paper studies the information transfer process during the iterative detection.2. In order to facilitate the following discussion, this thesis analyzes the existent detection algorithm of IDMA and introduces the performance estimation scheme.3. Under the precondition of no performance losing, in order to reduce the number of iteration times, this thesis introduces TR technology into IDMA, TDR-IDMA.Finally, this paper presents the simulation result of the performances of TDR-IDMA using C model and implements the IDMA detection algorithm on FPGA under the scenario of two users communicate synchronously. Also an implementation structure about TDR-IDMA iterative detection is introduced.