On the MIMO Channel Capacity of Multi-Dimensional Signal Sets

In this contribution we evaluate the capacity of Multi-Input Multi-Output (MIMO) systems using multi-dimensional PSK/QAM signal sets. It was shown that transmit diversity is capable of narrowing the gap between the capacity of the Rayleigh-fading channel and the AWGN channel. However, since this gap becomes narrower when the receiver diversity order is increased, for higher-order receiver diversity the performance advantage of transmit diversity diminishes. A MIMO system having full multiplexing gain has a higher achievable throughput than the corresponding MIMO system designed for full diversity gain, although this is attained at the cost of a higher complexity and a higher SNR. The tradeoffs between diversity gain, multiplexing gain, complexity and bandwidth are studied

Lower bounds for the stable marriage problem and its variants

In an instance of the stable marriage problem of size n, n men and n women each ranks members of the opposite sex in order of preference. A stable marriage is a complete matching M = {(m_1, w_i_1), (m_2, w_i_2), ..., (m_n, w_i_n)} such that no unmatched man and woman prefer each other to their partners in M.A pair (m_i, w_j) is stable if it is contained in some stable marriage. In this paper, we prove that determining if an arbitrary pair is stable requires Ω(n^2) time in the worst case. We show, by an adversary argument, that there exists instances of the stable marriage problem such that it is possible to find at least one pair that exhibits the Ω(n^2) lower bound.As corollaries of our results, the lower bound of Ω(n^2) is established for several stable marriage related problems. Knuth, in his treatise on stable marriage, asks if there is an algorithm that finds a stable marriage in less than Θ(n^2) time. Our results show that such an algorithm does not exist

Investigation of the utilisation of social networks in e-learning at universities

Over the years universities have considered to use social networks for learning purposes as most of their students now engage on them. However, questions on the impact social networks would have on learning and how they can be utilised further for more effective teaching and learning are still unclear. To solve these questions, an in-depth investigation has been conducted to understand the benefits and drawback of social network features available for students. The investigation results show that students strongly believe that social network features will help enhance learning and the key ways of utilising such features have been suggested

Precoder-Aided Iterative Detection Assisted Multilevel Coding and Three-Dimensional EXIT-Chart Analysis

A novel three-dimensional (3D) EXIT chart is developed for investigating the iterative behaviour of Multilevel Coding (MLC) invoking Multistage Decoding (MSD). The extrinsic information transfer characteristics of both the symbol-to-bit demapper used and those of the differentprotection constituent decoders suggest that potential improvements can be achieved by appropriately designing the demapper. The proposed 3D EXIT chart is then invoked for studying the precoder-aided multilevel coding scheme employing both MSD and Parallel Independent Decoding (PID) for communicating over AWGN and uncorrelated Rayleigh fading channels with the aid of 8PSK modulation. At BER=10?5, the precoder was capable of enhancing the achievable Eb/N0 performance by 0.5dB to 2.5dB over AWGN and Rayleigh channels, respectively