Special Issue Article
Improving the Quality of Experience by Optimization of Access Selection and Priority Scheduling (OASPS) In Heterogeneous Wireless Access Networks
The IEEE 802.16j standard for WiMAX has recently received considerable attention. The IEEE 802.16j amendment is fully compatible with the 802.16e standard and enhances IEEE 802.16e by incorporating relay technology . A typical IEEE 802.16j network consists of base stations (BSs), relay stations (RSs) and subscriber stations (SSs). The radio links between BSs and RSs are called relay links, while the links between BSs and SSs or between RSs and SSs are called access links. According to the channel qualities of these links, BSs and RSs can dynamically adapt the downlink modulation and coding schemes (MCSs) for data transmission. We design an ANS mechanism that takes into account all aspects of the trade-off between the quality of the connections, the preferences of the end users and the cost. To improve the quality of experience, priority scheduling is established between various call patterns. To highlight the benefits of our approach from the perspectives of both end users and network operators, we have implemented and tested the solution in a multitechnology simulator. Results show that the proposed solution outperforms mainstream approaches. We propose a modified priority algorithm for the uplink scheduler of Mobile WiMAX. The proposed algorithm guarantees the delay property of the real-time traffic by imposing a threshold to the bandwidth request messages of the non real-time Polling Service (nrtPS). Each service class is serviced exhaustively (until empty) to overcome on the starving of lower priority service class which is the Best Effort (BE). The threshold value can be adjusted according to the load demand of the networks. Simulation results, found at the end of this study show that the proposed algorithm is fairer and delivers higher throughput of the BE service class.