A study on uplink slot assignment scheme for DS-CDMA/TDD based asymmetric radio communication systems

摘要

This paper proposes an uplink slot assignment scheme for DS-CDMA/TDD based asymmetric wireless access scheme to support wireless multimedia communication service. In the proposed system, a default frame allocates a lot of resources for the downlink, and uplink/downlink radio resource ratio is autonomously controlled in each cell according to the amount of uplink traffic. To mitigate interference between uplink and downlink of neighboring cells due to such autonomous radio resource control in each cell, the proposed scheme applies a punctured convolutional code in the downlink in which the deleted bits are mapped on the last part of each frame, and branch metric for a part of punctured bits are forced to zero when they are suffered from high level mobile station to mobile station interference. On the other hand, in the uplink, the proposed scheme employs a slot assignment scheme that minimizes outage probability in the cell as well as interference to the downlink channels in the neighboring cell. Computer simulation confirms that the proposed system works well even when each cell autonomously change radio resource ratio between uplink and downlink.