The Research On Multiple-access Performance Of Underwater FH-CDMA Network

With the development of human civilization, people consume more and more resource. In order to sustain further development, we must know, utilize and exploit ocean resource. The related fields include the exploitation of seabed oil, the exploitation of ocean biology, ocean building, the use of ocean space, ocean power generation and so forth. All these fields are connected to underwater acoustic technique. With the acceleration of the ocean exploitation, the needs of underwater sense network, underwater monitor system and underwater alarm network are more and more urgent.This thesis analyzes the performance of FH-CDMA network. The major work includes:1 Model a channel that is characteristic of the complexity, variety, multi-path, high noise and bandwidth limit of underwater acoustic channel.2 Briefly introduce the principle and parameters of frequency-hopping system, research on the FH-CDMA component and key technique.3 Compare the auto-correlations, inter-correlations, hopping intervals, processing gains, collision probabilities of three different frequency hopping sequences—m sequence, once repeated sequence and chaos sequence.4 The author uses Markov model to evaluate the throughput and delay of uncoded system. Because the Markov model can't evaluate the coded system, we propose another precise model to evaluate the collision probability of coded system.5 Use OPNET Modeler to model the underwater acoustic channel and CDMA mechanism, then build the underwater acoustic network that is consisted of 7 nodes and evaluate the throughput and delay of the system in different situation.