Journal of Green Engineering- Special Issue
Cód:
491_9788792329332
Demand for wireless data exchange is perpetually increasing, leading to pressure on deployed wireless capacity. As systems enhance their spectral efficiency to attempt to address this, evermore complex processing techniques are being employed. Such techniques increase power consumption, leading to greater heat output from processers in network elements and increasing powered cooling. Moreover, the requirement for wideband linearity of radio frequency circuitry in state-of-the-art OFDM systems, twinned with high transmission power capability on the network side and the inefficiencies of components when operating at such limits, leads to greater inefficiency hence further heat power output and the need for greater cooling. All of these ingredients significantly affect the power consumption of communications equipment. Indeed, merely considering raw transmission power, the Shannon-Hartley theorem implies that necessary transmission power increases exponentially with required capacity.Such power consumption issues can be mitigated through cognitive radio (CR) techniques. The use of greater bandwidths through CR and in some cases the aggregation of bandwidths, as well as the opportunistic use of spectrum of more appropriate propagation characteristics or with better interference management, can reduce necessary transmission power for devices and systems. Moreover, CR techniques may achieve greater spatial/temporal awareness of connectivity options and their inherent power consumptions, as well as the power consumptions of chosen radio access characteristics. They might be able to use this awareness to dynamically switch to connections that better manage loads and interference, or might be able to minimize the power consumption of radio frequency circuitry through switching radio access technique given a required traffic load. At a simpler level, they may be able to appropriately select nearer connectivity options minimizing path loss/shadowing hence necessary tra
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