Last-generation and future wireless communication standards, such as DVB-T2 or DVB-NGH, are including multi-antenna transmission and reception in order to increase bandwidth efficiency and receiver robustness. The main goal is to combine diversity and spatial multiplexing in order to fully exploit the multiple-input multiple-output (MIMO) channel capacity. Full-rate full-diversity (FRFD) space-time codes (STC) such as the Golden code are studied for that purpose. However, despite their larger achievable capacity, most of them present high complexity for soft detection, which hinders their combination with soft-input decoders in bit-interleaved coded modulation (BICM) schemes. This article presents a novel low-complexity soft detection algorithm for the reception of FRFD space-frequency block codes in BICM orthogonal frequency-division multiplexing (OFDM) systems. The proposed detector maintains a reduced and fixed complexity, avoiding the variable nature of the list sphere decoder (LSD) due to its dependence on the noise and channel conditions. Complexity and simulation-based performance results are provided which show that the proposed detector performs close to the optimal log-maximum a posteriori (MAP) detection in a variety of DVB-T2 broadcasting scenarios.

Recent and next-generation wireless broadcasting standards, such as DVB-T2 or DVB-NGH, are considering distributed multi-antenna transmission in order to increase bandwidth efficiency and signal quality. Full-rate full-diversity (FRFD) space-time codes (STC), such as the Golden code, have been reported to be excellent candidates, being their main drawback their detection complexity, which is enhanced when soft output is required when combined with a bit interleaved coded modulation (BICM) scheme based on low-density parity check (LDPC) codes. We present a novel low-complexity soft detection algorithm for the reception of Golden codes in LDPC based orthogonal frequency-division multiplexing (OFDM) systems. Complexity and simulation-based performance results are provided which show that the proposed detector performs close to the optimal detector in a variety of DVB-T2 broadcasting scenarios.

In this paper, a new fast adaptive blind channel estimation method is proposed using the subspace information from the correlation matrix. The algorithm is fully adaptive in the sense that both the subspace information and the optimization which leads to the channel estimation are computed adaptively. It is based on the recently proposed YAST subspace tracker which has been shown to outperform other methods both in terms of speed of convergence and computational complexity. A discussion on the convergence properties of the proposed algorithm is presented. We also propose a hybrid method which makes use of the YAST subspace tracker for initial fast convergence and the subspace information is then updated using the numerically stable OPAST subspace tracker.

There are numerous mechanisms to guarantee the quality of service (QoS) of a wireless transmission. In many cases, the application layer sends hard-QoS requirements to the lower layers without negotiation. These requirements, which are defined by specific numeric values, are usually not fulfilled because of mobility or the delay between the signalling and data send procedures. Therefore, in wireless ad hoc networks, it is necessary to define a new conceptual model that changes the traditional vision of QoS integration. A new architecture is proposed; it is based on integration of the cross-layer concept and priority queueing. In this architecture, one node is aware of the state of other components of the network. The information shared between nodes includes the medium access control (MAC) layer metrics (MLM) and the network layer metrics (NLM). The NLMs contain the network topology, path gains and transmission power, while the MLMs contain the MAC layer buffer state. The case examined is a mobile wireless ad hoc network utilising smart antennas and spatial reuse TDMA. With this methodology, scheduling is improved and different QoS services are offered by using the information obtained by the cross-layer structure. Simulation results are presented for an STDMA network, with and without the new structure, and its feasibility is analysed.