A Link Adaptation Scheme to Support Relative DiffServ QoS over CDMA Radio Systems

A link adaptation schemes is proposed to improve the efficiency to support relative DiffServ QoS traffic over CDMA air interface. To differentiate the resource allocation between DiffServ PHBs and between the in/out profile packets within each AF class, two-level differentiation is done in the proposed scheme: inter-class differentiation and intra-class differentiation. In the inter-class resource differentiation, an adaptation based on delta modulation is proposed to allocate the resource based on their relative QoS parameters. The intra-class scheme is carried out priority queuing and rate adaptation in order to give further differentiation on the in/out packets and make full use of resource allocated through inter-class resource differentiation. Then each class´s delay in the current frame is feedback to the proposed delta modulation scheme at the inter-class level for resource in the following frame. Thus through this interaction between the two levels, a better QoS balance between classes is achieved and therefore a higher capacity is gained as shown by our numerical evaluation.