Olayinka Adigun

Energy efficiency analysis for MIMO transmission schemes in LTE

The demand for higher data rates in wireless communication systems has become inevitable with the availability of diverse range of multimedia applications in mobile communications today. Multiple Input Multiple Output (MIMO) antennas is one of the technologies utilized to support the required higher data rates in wireless communications. However, energy efficiency in cellular communications has generated lots of interest recently. Energy efficiency metrics will provide a yardstick for comparison and a pathway towards achieving the objectives of green communications in cellular networks. This paper investigates the energy efficiency of different MIMO transmission schemes applicable in 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) and compares them with each other and SISO transmission. The Energy Consumption Rating (ECR) of the various MIMO schemes are derived and discussed.

Towards a scalable routing approach for Mobile Ad-hoc Networks

The Internet is evolving towards a two-fold architecture that will comprise of traditional infrastructure based networks as well as emerging self organised autonomic peripheral networks. Such Internet peripheral networks are being termed as the Internet of things (IoT) whereby smart objects and devices will be connected together in a fully distributed fashion to provide ubiquitous services through pervasive networking. Mobile Ad hoc Networks (MANETs) is regarded as one of the pervasive self-organised networks that will play a major role in autonomic future internet communication. There are several wellknown challenges to be addressed in order to enable MANET deployments of large islands of interconnected smart devices. Therefore, in this paper, we perform simulations using the ns-2 software, for various well-known routing protocols for MANETs in order to determine the scalability of these protocols. This paper analyses the scalability of the routing protocols with respect to routing overhead required by approaches while also considering the packet delivery latency, which is an important Quality of Service (QoS) metric.

Sensing Optimization in Cooperative Cognitive Radio Networks

Cooperative spectrum sensing is a key function in cognitive radio networks in order to provide unused spectrum access opportunities and mitigate the impact of interference to the primary networks. Cooperative sensing can incur additional cooperation overhead, increased energy consumption, extra sensing time and delay in heterogeneous networks. In this paper, the sensing time period is optimized to minimize energy consumption in a diverse cooperative network using square law combining decision rule. The evaluation results confirm significant improvement in the sensing time and sensing task energy consumption.

Entropy-based opportunistic spectrum access for cognitive radio networks

This paper proposes an opportunistic spectrum decision scheme based on the weighted residual entropy concept for cognitive radio networks. The proposed scheme maximum entropy channel access selects appropriate spectrum opportunities based on the usefulness of the idle-channel remaining lifetime estimated through the weighted residual entropy function for the unoccupied channels. The performance of the proposed spectrum decision scheme is evaluated using a wealth of efficiency metrics, namely channel utilisation, channel collision, spectrum handoff rate and collision probability in perfect and imperfect spectrum sensing environments. The probabilities of primary signal detection and false detection are taken into the proposed spectrum hole selection technique. Despite the increasing probability of false detection, simulation results show that this central spectrum decision scheme greatly improves spectrum utilisation when the stated performance metrics were compared with those of known spectrum decision schemes such as random channel access, first-opportunity channel access and maximum remaining lifetime. Copyright

Next-generation communication systems for PPDR: the SALUS perspective

Abstract Public Protection and Disaster Relief (PPDR) agencies in European member states currently rely on digital Private Mobile Radio (PMR) networks for mission critical operations. PMR networks are based on two main standards for Europe: Terrestrial Trunked Radio (TETRA) and TETRAPOL. These networks provide secure and resilient mobile voice services, as well as basic data services. However, these traditional PMR networks show substantial limitations, when matched against modern requirements of PPDR agencies, including broadcast communications, dynamic secure groups, secure roaming, and emerging safety and security applications. Moreover, there are significant interoperability constraints when using multiple technologies, such as inter-technology coverage limitations, which can result in ineffective management of emergency events, both at national level as well as in cross-border regions.

Radio Spectrum Issues and Cognitive Mobile Computing

The rapid proliferation of mobile wireless devices, astronomical data traffic transmission and development of multifarious technologies has resulted in huge demand for usable radio spectrum bands. Allocation of new spectrum bands and maximizing the usage of currently allocated radio spectrum bands have become of vital importance in emerging mobile computing networks. This chapter highlights the importance and issues of radio spectrum in mobile computing networks and also presents cognitive functionalities as an appropriate solution to cope with the scarcity of usable radio spectrum in emerging cognitive mobile computing networks.

Feedback information and energy efficiency of MIMO transmission modes in LTE

Feedback information provides a leverage for improving the system performance of wireless communication systems. This paper investigates the effects that feedback information in terms of Channel Quality Information (CQI), Precoding Matrix Indicator (PMI) and Rank Indicator (RI) have on the energy efficiency of two popular Multiple Input Multiple Output (MIMO) transmission modes; Open Loop Spatial Multiplexing (OLSM) and Closed Loop Spatial Multiplexing (CLSM) in the downlink of 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE). This paper introduces an energy efficiency metric: Energy Consumption Rating (ECR) and present results for multi-user MIMO scenarios in a (2×2), (4×2) and (4×4) antenna configurations. The results from simulations carried out show that feedback information is essential to optimize system throughput and energy efficiency as the CLSM configurations, which utilizes all available feedback information shows significant energy efficiency gain over OLSM.

A multipath mobile ad-hoc routing protocol for enhanced reliability in lossy communications

Reliability of communication in unpredictable environments with increased complexity and lossless properties is one of the main objectives in wireless communication technologies. The autonomous nature of Mobile Ad hoc Networks (MANETs) classifies them as an effective solution to address emergency situation scenarios, such as rescue or disaster relief operations that take place in hostile and hazardous environments. This paper proposes a multipath approach based on the proactive Optimized Link State Routing (OLSR) protocol called RESCUE OLSR (R-OLSR), designed as an initial approach of the EU-ICT RESCUE project. The protocol exploits its capability to identify and transmit data via multiple paths based on two different relay approaches named Simple Relay Routing (SRR) and Advanced Relay Routing (ARR). The protocols efficiency is substantiated through a simulation scenario within a MANET using the NS-3 simulator. The acquired results indicate that a partial flooding of data increases the probability of receiving correct packets, improving the transmission reliability and routing performance.

Secure and interoperable communication infrastructures for PPDR organisations

The growing number of events affecting public safety and security (PS&S) on a regional scale with potential to grow up to large scale cross border disasters puts an increased pressure on agencies and organisation responsible for PS&S. In order to respond timely and in an adequate manner to such events, Public Protection and Disaster Relief (PPDR) organisations need to cooperate, align their procedures and activities, share the needed information and be interoperable. Existing PPDR/PMR technologies such as TETRA, TETRAPOL or P25, do not currently provide broadband capability nor is expected such technologies to be upgraded in the future. This presents a major limitation in supporting new services and information flows. Furthermore, there is no known standard that addresses interoperability of these technologies. In this contribution the design of a next generation communication infrastructure for PPDR organisations which fulfills the requirements of secure and seamless end-to-end communication and interoperable information exchange within the deployed communication networks is presented. Based on Enterprise Architecture of PPDR organisations, a next generation PPDR network that is backward compatible with legacy communication technologies is designed and implemented, capable of providing security, privacy, seamless mobility, QoS and reliability support for mission-critical Private Mobile Radio (PMR) voice and broadband data services. The designed solution provides a robust, reliable, and secure mobile broadband communications system for a wide variety of PMR applications and services on PPDR broadband networks, including the ability of inter-system, interagency and cross-border operations with emphasis on interoperability between users in PMR and LTE.