Abstract-Interest in broadband wireless access (BWA) has been growing due to increased user mobility and the need for data access at all times. IEEE 802.16e based WiMAX networks promise the best available quality of experience for mobile data service users. Unlike wireless LANs, WiMAX networks incorporate several quality of service (QoS) mechanisms at the Media Access Control (MAC) level for guaranteed services for data, voice and video. The problem of assuring QoS is basically that of how to allocate available resources among users in order to meet the QoS criteria such as delay, delay jitter and throughput requirements. IEEE standard does not include a standard scheduling mechanism and leaves it for implementer differentiation. Scheduling is, therefore, of special interest to all WiMAX equipment makers and service providers. This paper discusses the key issues and design factors to be considered for scheduler designers. In addition, we present an extensive survey of recent scheduling research. We classify the proposed mechanisms based on the use of channel conditions. The goals of scheduling are to achieve the optimal usage of resources, to assure the QoS guarantees, to maximize goodput and to minimize power consumption while ensuring feasible algorithm complexity and system scalability.

We present a simple analytical method for capacity evaluation of IEEE 802.16e Mobile WiMAX networks. Various overheads that impact the capacity are explained and methods to reduce these overheads are also presented. The advantage of a simple model is that the effect of each decision and sensitivity to various parameters can be seen easily. We illustrate the model by estimating the capacity for three sample applications—Mobile TV, VoIP, and data. The analysis process helps explain various features of IEEE 802.16e Mobile WiMAX. It is shown that proper use of overhead reducing mechanisms and proper scheduling can make an order of magnitude difference in performance. This capacity evaluation method can also be used for validation of simulation models.

Abstract-Mobile WiMAX systems based on the IEEE 802.16e standard require all downlink allocations to be mapped to a rectangular region in the two dimensional subcarrier-time map. Many published resource allocation schemes ignore this requirement. It is possible that the allocations when mapped to rectangular regions may exceed the capacity of the downlink frame, and the QoS of some flows may be violated. The rectangle mapping problem is a variation of the bin or strip packing problem, which is known to be NP-complete. In a previous paper, an algorithm called OCSA (One Column Striping with nonincreasing Area first mapping) for rectangular mapping was introduced. In this paper, we propose an enhanced version of the algorithm. Similar to OCSA, the enhanced algorithm is also simple and fast to implement; however, eOCSA considers the allocation of an additional resource to ensure the QoS. eOCSA also avoids an enumeration process and so lowers the complexity to O(n 2 ).

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