Access Control And Resource Allocation Scheme For Wide-band IDMA-based Satellite Communication Systems

Due to the limitation on frequency spectrum and payload capacity, widebandsatellite communication network is a typical bandwidth-constrained,power-constrained and onboard processing capability-constrained system. Hence, itis an important issue for satellite communications to utilize the limited resourcescientifically and make efficient use of the scarce onboard communication resources,while guaranteing different kinds of quality of service (QoS) requirements as well.The choice for multiple access (MA) scheme is the key to the above problem. Theemerging interleave-division multiple access (IDMA) technology can supportmulti-user with low computational complexity and without complicatedtransmission scheduling. Additionally, it has high bandwidth and power utilization.Furthermore, it can provide better multimedia service when the resouces are limited.Thus, considering the bottlenecks of wideband satellite systems and advantage ofIDMA technoloy, IDMA is introduced into satellite communication systems.Consequently, a novel medium access control (MAC) protocol is introduced for thepromising system based on our proposed QoS architecture. The power allocationscheme, rate adaptation and call admission control (CAC) scheme are designed asintegrated part of the MAC protocol, working together to improve the systemperformance.Firstly, in order to improve the efficiency and reduce the access delay in therandom access channel (RACH), the interleaver-division slotted-ALOHA (IDSA)method is adopted to alleviate the collision of access requests. Further, a novelminimum-power allocation scheme is developed to maximize the capacity of suchan interference-sensitive system. The key idea behind the scheme is to takeadvantage of signal to interference and noise ratio (SINR) Evolution technique inthe process of resource estimation, which is developed from the effectivechip-by-chip multiuser detection (CBC MUD) process in IDMA systems. Based onthis semi-analytical technique, the allocated power and interference level can befurther reduced when accurately evaluating the MUD effect on IDMA systems.Then, the rate adaptation scheme is illustrated to make the best use of onboardresources, through which each user can transmit at the highest availabletransmission rate. To further enhance the performance of the MAC protocol, twodifferent CAC schemes, namely interference based uplink CAC and downlink CACbased on onboard maximum transmitted power, are implemented respectively.Considering the long propagation delay in satellite systems, power control error (PCE) is another inevitable issue. The proposed CAC scheme also takes into accountthe effect of PCE to make more ccurate admission decisions in satellitecommunication environments.Analysis and simulation results show that, by taking full advantage of CBCMUD technique, the proposed IDMA MAC protocol achieves high throughput andlow average packet delay. Additionally, based on the SINR Evolution, the MAC canmake resource estimation considering the effect of MUD accurately, leading to alow outage probability as well as low blocking probability.