In this paper, we propose a novel cross layer scheme to lower power consumption of ADCs in OFDM systems, which is based on resolution adaptive ADCs and Fountain codes. The key part in the new proposed system is that the dynamic range of ADCs can be reduced by discarding the packets which are transmitted over ''bad'' sub carriers. Correspondingly, the power consumption in ADCs can be reduced. Also, the new system does not process all the packets but only processes surviving packets. This new error correction layer does not require perfect channel knowledge, so it can be used in a realistic system where the channel is estimated. With this new approach, more than 70% of the energy consumption in the ADC can be saved compared with the conventional IEEE 802.11a WLAN system under the same channel conditions and throughput. The ADC in a receiver can consume up to 50% of the total baseband energy. Moreover, to reduce the overhead of Fountain codes, we apply message passing and Gaussian elimination in the decoder. In this way, the overhead is 3% for a small block size (i.e. 500 packets). Using both methods results in an efficient system with low delay.
|Number of pages||10|
|Journal||EURASIP journal on wireless communications and networking|
|Publication status||Published - 1 Feb 2009|