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We propose in this work a new state-dependent admission control scheme where the degree of acceptance of flows depends on the density of the users in a given location. The latter refers to different areas in a single OFDMA-based WiMAX cell wherein users are allowed to move internally between those areas as well as externally to other cells. We develop an analytical model which allows us to derive...
We investigate in this paper the impact of mobility on the capacity of an OFDMA-based mobile WiMAX network in the presence of two types of flows: streaming and elastic, under a dynamic configuration where users come to the system following a Poisson process and leave it after a finite duration. This duration is independent on the amount of resources for streaming flow, such as voice, and proportional...
OFDMA-based IEEE802.16 implements among other features adaptive modulation and coding (AMC) which results in a different bit rate for each user depending on its position in the cell as well as the radio condition it experiences; users away from the base station experience lower throughput. In case of (intra-cell) mobility, the download time for the data user will thus depend on the different locations...
We study in this paper the capacity of the downlink of OFDMA-based IEEE802.16 WiMAX system in the presence of two types of traffic, streaming and elastic. We focus in particular on the impact of Adaptive Modulation and Coding (AMC) as well as inter-cell interference resulting from different frequency reuse schemes. Several performance measures, namely blocking rates, mean transfer time and the mean...
In this paper, we propose a secure spread spectrum communication systems, using chaotic spreading sequences. The main advantages of such usage are the increased security of the messages and also the number of users in the system. The low dimension of the chaos, generated in Chua's circuit suggests a low degree of randomness in the chaotic signal. A digital chaotic codec is then developed to increase...
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