Design of MAC Protocol for QoS Guarantee QoS in a CDMA System

• Main Authors: Wei-Shang Chang, 張維升
• Other Authors: Tsern-Huei Lee
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/68238551606607934965

碩士 === 國立交通大學 === 電信工程系 === 87 === For next-generation multi-services CDMA wireless system, CDMA has inherent capacity to control the quality-of-services (QoS) requirements by assigning different power levels to each traffic type. Toward this, optimum power control schemes have been investigated. The three components of QoS are bandwidth (rate), delay, and reliability. The delay aspect of QoS specification will not be discussed in the power controlled CDMA system. The delay issue has to be considered in connection with the definition of service class, call admission control schemes, and scheduling algorithms. To guarantee delivery of packets with time constraints, several access control schemes had been proposed in [1]. These access schemes totally eliminate the possibility of packet loss caused by collision. From the results of [1], the DP (Dynamic Priority) scheme seems to be a good choice for an integrated voice/data system. The DP scheme, however, must insert the Deadline information into the transmitted packet and the BS sorts the Deadline information of all users. After sorting the Deadline information, the BS know which user has higher priority and sent ACK messages to high priority users. Users transmit one packet at the head of its buffer in the adequate power level when receiving ACK message from the BS. According to the principle of the DP scheme, we propose a Distributed Priority Assignment scheme to reduce the complexity of both mobiles and base station. This maybe a solution of future QoS based wireless CDMA network.