QoS Consideration and Frame Allocation Algorithm for OFDMA Scheduling
Date Issued
2010
Date
2010
Author(s)
Wang, Wen-Hsin
Abstract
Orthogonal Frequency Division Multiple Access (OFDMA) has become a very popular technique in wireless communication systems such as the IEEE 802.16e and the OFDMA frame structure has triggered a series of research trends in recent years. In the IEEE 802.16e standard, every burst we transmitted to a particular user must be a rectangle in a two-dimensional frame constructed by sub-channel and time slot. If too many bursts are backlogged at the same time, not all bursts can be sent in the next frame and additional delay occurs. In other words, the system should arrange the burst transmitted in an OFDMA frame efficiently in order to assure limit delay and maintain high throughput. Although there are previous works in resolving the packet scheduling of OFDMA bursts, we proposed a new downlink map allocated algorithm to decide the maximum information bits which can be transmitted in one OFDMA frame by using the technique of genetic algorithm and heuristic pallet loading algorithm. Furthermore, we consider various QoS requirements for different applications in OFDMA wireless communication systems. For this purpose, we combine QoS and allocation algorithm to make the proposed design more practical. The simulation results show that we can allocate at least 86% of slots in an OFDMA frame when the number of genetic generations is more than 5. Moreover, we can execute less times in genetic algorithm to reduce the computational time when there are too many packets in the buffer. In addition, we successfully adopt the stochastic-network-server model to estimate the resulting packet delay. Comparing with deterministic-network-server model, our stochastic-network-server model can provide predictions more explicitly about its probabilistic behavior of packet delay in any threshold.
Subjects
QoS
OFDMA
Scheduling
802.16e
Type
thesis
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