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Tone Injection Essay

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This technique increases the constellation size so that each of the point in the original basic constellation can be mapped into several equivalent points in the expanded constellation. Since substituting a point in the basic constellation for a new point in the larger constellation is equivalent to injecting a tone of the appropriate frequency and phase in the multicarrier signal, therefore, this technique is called tone injection. The extra degrees of freedom, which is generated as each symbol in the data block can be mapped into one of the several equivalent constellation points, can be utilized for peak to average power ratio reduction. The distance between the original and extended points is D. The receiver remains unaltered. D is …show more content…

Various works are available in literature mainly focusing on complexity reduction of optimization problem. A gradient algorithm is proposed where the gradient of clipping noise mean square error is calculated and optimization of signal to clipping noise ratio is done in place of peak to average power ratio and order of complexity is O(N). A truncated IDFT algorithm is proposed where in place of calculating entire IDFT values, it calculates on maximal IDFT element thus reducing complexity of optimization process. The basic idea is to divide the group in two halves of N/2 and leave the half with lesser energy and move in similar way till we reach the maximum energy element, however this scheme may not always give correct maximal IDFT element, it also costs in lower peak to average power ratio reduction. For designing the peak cancelling signal clipping noise is analysed and several iterations of clipping and filtering are used till desired peak cancellation signal is generated. References also proposed an adaptive-scaling algorithm and constant-scaling algorithm for tone reservation. LSA-TR method with fast convergence is proposed which is based on least square approximation and used to find the peak cancelling signal faster than clipping control TR method. References used genetic algorithm to find the optimal PRC set, it also discussed an adaptive amplitude clipping tone reservation algorithm (AAC-TR) to solve the optimization

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