Deadline dependent coding-a framework for wireless real-time communication

A framework for real-time communication over a wireless channel is proposed. The concept of deadline dependent coding (DDC), previously suggested by the authors, is further developed using soft decision decoding of block codes to maximize the probability of delivering information before a given deadline. The strategy of DDC is to combine different coding and decoding methods with automatic repeat request (ARQ) in order to fulfil the application requirements. These requirements are formulated as two quality of service (QoS) parameters: deadline (t/sub DL/) and probability of correct delivery before the deadline (Pd), leading to a probabilistic view of real-time communication. An application can negotiate these QoS parameters with the DDC protocol, thus creating a flexible and dependable scheme.