Chunk-Based Resource Allocation in OFDMA Systems—Part II: Joint Chunk, Power and Bit Allocation

TLDR

Grouping adjacent subcarriers into chunks enables chunk‑by‑chunk resource allocation, reducing complexity in OFDMA systems. The paper proposes a joint chunk, power, and bit allocation scheme that maximizes throughput under a total transmit‑power constraint. The authors introduce a scaling factor and a digitization process to convert theoretical bit allocations to integers, and study the impact of system parameters while comparing dynamic and fixed power allocation schemes. Numerical results show that while theoretical throughput of fixed and dynamic power schemes is similar, the digitized dynamic allocation yields higher average throughput than the fixed scheme.

Abstract

By grouping a number of adjacent subcarriers into a chunk, resource allocation can be carried out chunk by chunk in orthogonal frequency division multiple access (OFDMA) systems. Chunk-based resource allocation is an effective approach to reduce the complexity of resource allocation in OFDMA systems. In this paper, a chunk-based resource allocation scheme, i.e. joint chunk, power and bit allocation, is proposed and analyzed by maximizing the throughput under a total transmit power constraint. A scaling factor is introduced to achieve optimal allocation. Considering the digital nature of bits per symbol per subcarrier (bits/symbol/subcarrier), a digitization process is proposed to digitize the theoretically allocated bits/symbol/subcarrier to integer. System parameters, such as the power constraint, number of users, coherence bandwidth, number of subcarriers and number of chunks, are introduced and their impacts on the average throughput are studied. The performance of the dynamic power allocation scheme is compared with the fixed power allocation scheme. The numerical results show that the theoretical throughput of the fixed power allocation scheme is quite close to that of the dynamic power allocation scheme. However, when the digital nature of bits/symbol/subcarrier is considered, the average throughput of the dynamic power allocation outperforms the fixed power allocation scheme.