Link adaptation algorithms for improved delivery of delay- and error-sensitive packet-data services over wireless networks

Link Adaptation is a radio resource management technique that assesses the channel conditions and selects a transport mode, from a set of possible options, which is optimised for these conditions according to a predefined criterion. The optimum transport mode is commonly determined so as to maximise the throughput. Although this approach may be appropriate for best-effort services, its suitability for multimedia services, usually characterised by tight delay and error performance constraints, has been questioned. As a result, a number of alternative algorithms have been proposed in the literature. In this context, this paper presents and evaluates in a dynamic radio environment several Link Adaptation algorithms designed to enhance the provision of delay- and error-sensitive multimedia packet-data services over wireless systems. The obtained results demonstrate that significant improvements in terms of throughput, transmission delay, error performance and operation of Link Adaptation itself can be obtained with the proposed schemes.Postprint (published version

Design guidelines for spatial modulation

A new class of low-complexity, yet energyefficient Multiple-Input Multiple-Output (MIMO) transmission techniques, namely the family of Spatial Modulation (SM) aided MIMOs (SM-MIMO) has emerged. These systems are capable of exploiting the spatial dimensions (i.e. the antenna indices) as an additional dimension invoked for transmitting information, apart from the traditional Amplitude and Phase Modulation (APM). SM is capable of efficiently operating in diverse MIMO configurations in the context of future communication systems. It constitutes a promising transmission candidate for large-scale MIMO design and for the indoor optical wireless communication whilst relying on a single-Radio Frequency (RF) chain. Moreover, SM may also be viewed as an entirely new hybrid modulation scheme, which is still in its infancy. This paper aims for providing a general survey of the SM design framework as well as of its intrinsic limits. In particular, we focus our attention on the associated transceiver design, on spatial constellation optimization, on link adaptation techniques, on distributed/ cooperative protocol design issues, and on their meritorious variants