A Novel Criterion of Subcarrier Allocation for Grouped MC-CDMA Systems

This paper introduces a new adaptive subcarrier assignment criterion for downlink grouped Multi Carrier-Code Division Multiple Access (MC-CDMA) systems. The target of the allocation is to maximize system capacity. We mainly focus on how to partition subcarriers into groups and how to efficiently assign active users into these groups. Lagrangian multipliers are employed to cope with the optimization problem. Due to the polynomial problem of transmit power for each user, we can not obtain the solution easily. Fortunately, we are able to obtain the near solution by an approximate formula and derive a near optimal allocation criterion for active users. Meanwhile, the proposed criterion is universal for any downlink subcarrier- grouping allocation schemes. Computer simulations demonstrate that the proposed criterion is efficient and feasible for practical systems.