The Radio Broadcast System Of Error Control Study

We investigate the error-control methods based on network coding and rateless coding. In the thesis, we investigate two efficient error control methods for wireless broadcasting system. Assuming perfect error detection, a transmission block is received either perfectly or is dropped. Then, the channels for the system can be modeled as block erasure channels. The content of this thesis can be divided into two main parts: one for network coding method and another one for deterministic rateless codes. We use transmission efficiency as the measurement to compare our approach with the existed methods.For the network coding schemes for wireless broadcasting, it was shown in previous literatures that network coding can improve the transmission efficiency of wireless broadcasting, compared to traditional ARQ schemes. We propose a new network coding scheme to further improve the efficiency. For complexity consideration, we limit our network codes as binary. We show that our coding scheme can actually achieve the theoretical performance bound for a sufficiently large number of information blocks. For the proposed scheme, we use the coding sets to collect the indexes of information blocks to be encoded during the retransmission period. The coding sets are evaluated by an index allocating algorithm which aims to minimize the number of the sets (and thus the number of retransmitted blocks). The numerical results from simulations show that our scheme has higher transmission efficiency than traditional ARQ, and than previous schemes using network coding.In the fourth chapter, we investigate the design of binary deterministic rateless codes (BDRCs) in wireless broadcasting systems. For the erasure channels, the BDRCs approximate to the property of maximal distance separable (MDS), and thus work quite efficiently. We study the design of the BDRCs for such wireless broadcasting systems. For the code redundancy, we derive the function of the probability of keeping the MDS property with redundancy as the variable, and investigate its property. Then, the redundancy is designed such that the high transmission efficiency and low system complexity are achieved. With limited feedback, we propose modified BDRCs, which use an error matrix to efficiently increase the transmission efficiency. We rank retransmitted blocks based on the users (dropped the blocks) to further improve the system performance. The numerical results show that the designed BDRCs without feedback have substantially better performance than LT codes, especially for finite source blocks. The proposed systems with feedback have better performance than ARQ. The performance gains are more pronounced with more users.At last, we discuss the future of the error control methods in the wireless broadcasting systems.