This paper gives a novel spatial and temporal Tomlinson Harashima Precoding (THP) algorithm based on concatenated processing for Multiple-Input Multiple-Output (MIMO) frequency selective fading channels. Generally spatial and temporal THP is jointly processed together, using joint optimization THP, and the complexity is very large. In this paper, we propose a novel spatial and temporal concatenated THP algorithm, firstly Spatial THP (S-THP) is performed to cancel spatial interference owing to different antenna or multiuser; then Temporal THP (T-THP) to each sub-channel of MIMO channel model is performed, through this step, MIMO Inter Symbol Interference (ISI) channel model is changed into flat fading MIMO channel. Using this solution, we can change the complex spatial and temporal THP into space and time domain concatenated THP, and in each space, the algorithm is relative simple. From algorithm analysis and performance comparison, we can see the validation and advantage of this method suggested in this paper.

In this paper, we investigate the performance of a dual-hop block fading cognitive radio network with underlay spectrum sharing over independent but not necessarily identically distributed (i.n.i.d.) Nakagami-m fading channels. The primary network consists of a source and a destination. Depending on whether the secondary network which consists of two source nodes have a single relay for cooperation or multiple relays thereby employs opportunistic relay selection for cooperation and whether the two source nodes suffer from the primary users' (PU) interference, two cases are considered in this paper, which are referred to as Scenario (a) and Scenario (b), respectively. For the considered underlay spectrum sharing, the transmit power constraint of the proposed system is adjusted by interference limit on the primary network and the interference imposed by primary user (PU). The developed new analysis obtains new analytical results for the outage capacity (OC) and average symbol error probability (ASEP). In particular, for Scenario (a), tight lower bounds on the OC and ASEP of the secondary network are derived in closed-form. In addition, a closed from expression for the end-to-end OC of Scenario (a) is achieved. With regards to Scenario (b), a tight lower bound on the OC of the secondary network is derived in closed-form. All analytical results are corroborated using Monte Carlo simulation method.

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