{HEAD ~ Channel detection} is accomplished by {TAIL ~ means} of counting the number of negative acknowledgements, which classifies the channel degradation level and determines which alternatives to be adapted in order to combat specific blockage phenomenon 
is accomplished by
{ HEAD ~ Channel detection } is accomplished by { TAIL ~ means } of counting the number of negative acknowledgements , which classifies the channel degradation level and determines which alternatives to be adapted in order to combat specific blockage phenomenon
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