In this paper we present a modification of a typical turbo code to allow for the header bits to be decoded much faster than the other bits. This gives the decoder a possibility to discard data packets not addressed to it, and saves time and power since fewer iterations need to be performed to reliably decode the header. The proposed algorithm frequently terminates the first trellis of the turbo encoder by inserting tail bits into the data sequence. The bits surrounding the termination sequences have much lower bit error rate and higher reliability than the other bits and can be used to store header information. Moreover, a tailored interleaver and puncturer design can increase the reliability of the header decoding even further. The algorithm is shown to decode the header bits at bit error rate of approximately 0.002 (at Eb/N0=3dB) after only one iteration. In addition, the proposed algorithm has lower memory requirements than the non-modified turbo decoding algorithm.
This paper introduces digital pulse interval modulation with dual header, a new form of digital pulse time modulation scheme offering increase transmission capacity, requiring less transmission bandwidth, and it has built-in frame and slot synchronisation capability. Theoretical expressions are describing the code characteristics and showing the advantages of this new scheme. Matlab is used to simulate the proposed scheme and a selection of waveforms are also presented.
Lyapunov stability-based adaptive backpropagation (LABP) for discrete systems is proposed in this paper. It can be applied to various aspects of adaptive signal processing. A Lyapunov function of the error between the desired and actual outputs of the neural network is first defined. Then the error is backward-propagated based on Lyapunov stability theory so that it can be used to adaptively adjust the weights of the inner layers of the neural networks. Subsequently, this will lead to an error between the desired and actual outputs converging to zero asymptotically. The proposed scheme possesses distinct advantages over the conventional BP by assuring that the system will not get stuck in local minima. Furthermore, this scheme has a faster convergence property and the stability is guaranteed by Lyapunov stability theory. A simulation example is performed to support the proposed scheme.
