One of the key foundations of smart grid (SG) is a reliable communications infrastructure which is a sophisticated, multi-layer network carrying different classes of data. SG communications needs to be designed to accommodate the current energy management requirements as well as the potential demand of future applications. In this paper, we propose the application of cognitive radio (CR) based on the IEEE 802.22 standard in the SG wide area networks (WANs). We discuss the benefits of the proposed scheme including opportunistic access of TV bands, extended coverage, ease of upgradability, self-healing and fault-tolerant design. The proposed scheme can work as a secondary radio particularly in urban areas and as a backup in disaster management. In rural areas, however, a stand-alone radio based on IEEE 802.22 can effectively provide broadband access because of the wide area coverage due to the good propagation characteristics of TV bands.
We consider a narrowband multiuser system in which several transmitting users are received through a synchronous, flat fading channel at an antenna array. The paper introduces a multiuser detection technique that combines groupwise detection with iteration. It is well suited to overloaded conditions, where there are more transmitter antennas than receive antennas. The soft decisions it uses internally also make it suitable as a detector in a concatenated structure. Its performance and computation can be traded off through selection of group size. A variant of the algorithm achieves further computation reduction by incorporating a soft sphere detection core.
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