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A new scheme for error-free transmission is presented which uses optimized combination of adaptive modulation and coding (AMC) and automatic repeat request (ARQ). Using conventional error correction codes with finite length, a limited value of packet error rate (PER) is inevitable. More powerful codes with more extra parity bits results in lower PER, however, at the cost of more transmit power per bit which is limited by average power constraint. Remained erroneous packets may be detected by error detection codes and be substituted by retransmission request in ARQ. However, when error correction capability is weak, throughput decreases due to increase of required retransmissions. In this article a method for optimum combination of error correction codes in AMC and error detection codes in ARQ is provided. In practice, due to estimation error and time variant channels, noisy and outdated channel state information (imperfect CSI) is available which restricts providing exact instantaneous PER constraint. To satisfy instantaneous PER constraint based on imperfect CSI, a novel technique is designed in this paper.Numerical evaluations indicate the efficiency of the proposed design.

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a new scheduling and link adaptation scheme is designed for a heterogeneous wireless network where a) different links are using the shared media with various throughput requirement based on their applications, b) links have different characteristics, c) various bit error rate constraints are to be considered at the receivers, d) based on the available power supplies different average transmission power constraints are to be met. A fuzzy based scheme with a low complexity is presented which may be implemented in a wide range of networks where channel's specifications are not available and network structure may be unknown. It is shown that the proposed fuzzy based scheme gives a close performance to analytical approach, however, with substantially lower CSI load and computational cost.