eOCSA: An algorithm for burst mapping with strict QoS requirements in IEEE 802.16e Mobile WiMAX networks

Abstract

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 ).

Scheduling in IEEE 802.16e mobile WiMAX networks: key issues and a survey

“…Instead only bin sizes are given. Second, with increasing number of bursts (number of bins), the other end of the big bin (left side of the WiMAX frame) in which [15] small bins are fitted also changes to allow increasing size of the variable part of DL MAP.…”

“…On the other hand, eOCSA has a slightly higher over-allocation because we try to fit rectangles in these small unused spaces. More details on this other tradeoffs in burst mapping are presented in [15].…”

Two-dimensional downlink burst construction in IEEE 802.16 networks

“…However, the traditional studies in operational research are not applicable for the burst construction because they focus on packing objects with fixed shapes and values [13][14][15]. Thus, a number of algorithms were proposed [10,11,[16][17][18][19][20][21]. The eOCSA algorithm proposed by So-In et al [10] constructs the first burst in the bottom right-hand corner of the available bandwidth area, and subsequently constructs another burst if the available bandwidth area above the previous burst is sufficient.…”

“…Thus, a number of algorithms were proposed [10,11,[16][17][18][19][20][21]. The eOCSA algorithm proposed by So-In et al [10] constructs the first burst in the bottom right-hand corner of the available bandwidth area, and subsequently constructs another burst if the available bandwidth area above the previous burst is sufficient. Otherwise, eOCSA subsequently constructs the burst on the left-hand edge of the previous burst.…”

“…Therefore, a number of researchers regarded the burst construction problem as a variant of the bin packing problem. So-In et al [10] designed the enhanced onecolumn striping with non-increasing area first mapping algorithm (eOCSA), which constructs each burst from bottom right to top left of the available bandwidth area. Wang et al [11] developed the weighted less flexibility first algorithm (WLFF), which constructs each burst on the best edge selected in the free bandwidth area.…”