An efficient downlink mapping algorithm for AMC mode in WiMAX systems

Abstract

This paper proposes an efficient downlink resource allocation scheme for Orthogonal Frequency Division Multiple Access based WiMAX systems using the Adaptive Modulation and Coding mode operation. Given a set of user requests, the proposed algorithm determines the modulation scheme and allocates a two-dimensional (time and frequency) burst to each user. It is known that finding the optimal solution for such a resource allocation problem is NP-complete. To reduce the computation complexity, this paper proposes a heuristic solution. Compared with the Efficient Downlink Bandwidth Allocation (EDBA) algorithm [6], the proposed scheme achieves higher channel utilization and system throughput with similar execution time. Simulation results show that the average channel utilization of the proposed scheme is about 75~85% and that of EDBA is about 60~70%.

A Downlink Mapping algorithm for two-level requests in IEEE 802.16e systems under AMC mode

“…To explore the multiuser gain under frequency selective channels, the AMC mode, where a subchannel consists of contiguous subcarriers, is often used to improve spectrum efficiency. The authors in [5] proposed a mapping algorithm considering the AMC mode and the rectangle constraint. However, [5] did not consider traffic differentiation in data mapping.…”

“…The authors in [5] proposed a mapping algorithm considering the AMC mode and the rectangle constraint. However, [5] did not consider traffic differentiation in data mapping.…”

“…In this section, we evaluate the performances of the EDMA [5] and the proposed algorithm via simulations. The investigated system is the DL of an OFDMA-based IEEE 802.16e wireless network under the AMC mode.…”

“…This paper proposes a heuristic DL mapping algorithm considering the rectangle constraint in the AMC mode with two-level requests. Simulation results show that, compared with EDMA [5], the proposed algorithm serves more urgent data than EDMA does. The rest of this paper is organized as follows.…”

“…The algorithms in [2]- [4] consider the PUSC permutation where the MCS of all subchannels are the same for a MS. Though the algorithms in [5]- [7] deal with the AMC permutation, traffic differentiation is not considered. This paper proposes a heuristic DL mapping algorithm considering the rectangle constraint in the AMC mode with two-level requests.…”