Omar Alani

Reducing the PAPR by utilisation of the LDPC code

Peak-to-average power ratio (PAPR) is a major drawback in most multi-carrier communication techniques such as orthogonal frequency division multiplex system (OFDM). OFDM consists of lots of independent modulated subcarriers, as a result the amplitude of such a signal can have very large values. These large peaks increase the amount of intermodulation distortion resulting in an increase in the error rate. The PAPR of an OFDM signal can be reduced in several ways: selective mapping, Golay sequences, cyclic coding, clipping and filtering, and multiple signal representation techniques. The authors have improved the performance of the OFDM system by using low-density parity-check (LDPC) codes as an alternative to turbo coding in mitigating the PAPR problem which has been used in the pervious works of the authors. The authors present the design for the proposed (LDPC) code technique that achieves good error correction performance and is used to lower the PAPR in a multiple-input multiple-output OFDM system. The simulation results show that 6-60- reduction in PAPR over current values in the literature can be achieved depending on the system type.

A smart disaster management system for future cities

Smart cities have recently become the mainstream approaches for urbanisation. Environmental, social and economic sustainability, digital inclusion and high quality of life are considered important elements in smart cities design. Emergency response system and resilience are among the most crucial dimensions of smart and future cities design due to the increase in various disruptions caused by frequent manmade and natural disasters such as September 2001 and Philippines Typhoon Haiyan 2013. Disasters cause great economic and human losses each year throughout the world. Transportations and Telecommunications play a crucial role in disaster response and management. Our research is focused on developing emergency response systems for disasters of various scales with a focus on transportation systems. We have proposed and evaluated a disaster management system that uses Intelligent Transportation Systems including Vehicular Ad hoc Networks (VANETs), mobile and Cloud Computing technologies. In this paper, we report our recent work on two major evacuation strategies, Demand Strategies (DS) and Speed Strategies (SS), which provide better evacuation results in smart cities settings.

Technologies for 5G Networks: Challenges and Opportunities

Mobile data traffic has grown substantially owing to the widespread use of data-hungry devices such as smart handsets and laptops. This has encouraged researchers and system designers to develop more efficient network designs. The authors review the technologies that can support speeds of multiple Gbps for future fifth-generation (5G) networks. They examine the many challenges, problems, and questions that arise in the research and design stage, and conclude that the anticipated high-traffic demands and low-latency requirements stemming from the Internet of Things (IoT) and machine-to-machine (M2M) communications can be met only with radical changes to the network paradigm. These include harnessing the millimeter-wave band for the dense deployment of small cells. Future wireless systems will include myriad smart features and applications to make 5G the most intelligent and dominant wireless technology thus far.

A Survey on Media Independent Handover (MIH) and IP Multimedia Subsystem (IMS) in Heterogeneous Wireless Networks

One challenge of wireless networks integration is to provide ubiquitous wireless access abilities and seamless handover for mobile communication devices between different types of technologies (3GPP and non-3GPP), such as Global System for Mobile Communication, Wireless Fidelity, Worldwide Interoperability for Microwave Access, Universal Mobile Telecommunications System and Long Term Evolution. This challenge is critical as mobile users are becoming increasingly demanding for services regardless of the technological complexities associated with them. To fulfil these requirements for seamless vertical handover (VHO) two main interworking frameworks have been proposed by IEEE Group and 3GPP for integration between the aforementioned technologies; namely, Media Independent Handover IEEE 802.21 and IP Multimedia Subsystem, where each of them requires mobility management protocol to complement its work, such as Mobile IP and Session Initiation Protocol, respectively. Various VHO approaches have been proposed in the literature based on these frameworks. In this paper, we survey the VHO approaches proposed in the literature and classify them into four categories based on these frameworks for which we present their objectives and performances issues.

Indoor airport radio-over-fiber network traffic model and performance analysis using load-balancing techniques [Invited]

The development of airports such as the recently inaugurated Heathrow Terminal 5, as well as the increasing number of people using these facilities every day for business reasons or just for pleasure, reveals the importance of adequate and reliable communication facilities in this context. This environment is characterized by multiservice, multistandard wireless technologies and a highly variable traffic demand in space and time due to passenger flow, behavior, and usage from the terminals entrance to the corresponding boarding gate, ruled by flight departure schedules, in the indoor environment. The Intelligent Airport (TINA) project establishes its objective as the creation of a seamless hybrid wireless and wired infrastructure capable of providing users with a wide range of services, based on radio-over-fiber (RoF) networks, anticipating the deployment of multiple air interfaces within 4G networks. In this paper the spatial and temporal traffic demand is analyzed and modeled through simulation, as a means of selecting the optimum location for the base stations/antenna units (BSs/AUs) in the network. A load-balancing technique is applied to ease the load on congested cells using strategically located fixed relay nodes, and the networks behavior is analyzed for different BS properties.

Algorithm for seamless vertical handover in heterogeneous mobile networks

One challenge of wireless networks integration is to provide ubiquitous wireless access abilities and seamless handover for mobile communication devices between different types of technologies (3GPP and non-3GPP) such as Wireless Fidelity (Wi-Fi), Worldwide Interoperability for Microwave Access (WiMAX), Universal Mobile Telecommunications System (UMTS) and Long Term Evolution (LTE). This challenge is critical as Mobile Users (MUs) are becoming increasingly demanding for improved services regardless of the technological complexities associated with them. To fulfill these requirements for seamless Vertical Handover (VHO) two main interworking frameworks were proposed by IEEE Group and 3GPP for integration between the aforementioned technologies; namely, Media Independent Handover IEEE 802.21 (MIH) and IP Multimedia Subsystem (IMS), where each of them requires mobility management protocol to complement its work such as Mobile IP (MIP) and Session Initiation Protocol (SIP), respectively. In this paper, we overview these frameworks and show their components, benefits and drawbacks. Then we present our Imperative Alternative MIH for Vertical Handover (I AM 4 VHO) algorithm based on MIH framework and using fuzzy logic to provide low connection failure (probability of session rejection) and low signaling cost for enhancing VHO in heterogeneous wireless networks environment. Simulation based performance evaluation shows that the proposed algorithm reduces the probability of VHO connection failure by up to 75%.

Peak-to-average power ratio reduction technique for MIMO/OFDM systems

Convolutional coding has been classically used in channel coding to provide Forward Error Correction (FEC) capability to the system by adding some carefully designed redundant information to the data being transmitted through the channel. However, in this work, we use convolutional codes for a different purpose: the reduction of the Peak-to-Average Power Ratio (PAPR) in an Orthogonal Frequency Division Multiplexing (OFDM) system by utilising these codes as spreading codes. This is an alternative to turbo coding and Low-Density Parity Check (LDPC) codes, which have been used for the same purpose in our previous works. The PAPR is a major drawback in most multicarrier communication techniques such as OFDM. OFDM consists of lots of independent modulated subcarriers; as a result, the amplitude of such a signal can have very large values. These large peaks increase the amount of intermodulation distortion, resulting in an increase in the error rate. The PAPR of an OFDM signal can be reduced in several ways: Selective Mapping (SLM), Golay sequences, cyclic coding, clipping and filtering and multiple signal representation techniques. Our results show that using LDPC coding in mitigating PAPR led to a 6%-60% reduction in this ratio, which is better than our proposed work based on either turbo coding or convolutional coding and the SLM and clipping techniques in the literature.

Service model and resource allocation scheme for multimedia traffic in 3G wireless systems

In this paper, we propose a multi-component teleservice model for multimedia applications. A Novel Resource Allocation Scheme for call and traffic management that exploits the multi-component teleservice is developed and analysed. The scheme was applied to hierarchical cellular structure networks. The performance is compared with the standard approach based on the single multimedia stream flow. The proposed scheme shows better performance in terms of reducing blocking and dropping probabilities.

Performance evaluation of DVB-RCT return path in fading channels with added diversity

The radio spectrum is a finite resource and it is important that all users exploit it efficiently. Consequently, modulation schemes used for the wireless environment should utilize the RF channel bandwidth, and the transmitted power, as efficiently as possible. Across Europe, the digital video broadcasting (DVB) group has proposed a technique for a high data-rate return path known as DVB-return channel through terrestrial (DVB-RCT) specifically for consumer device convergence (full Internet connectivity through a television set). The introduction of adaptive M-ary quadrature amplitude modulation (MQAM) into the DVB-RCT standards as opposed to static modulation (as used in the DVB-terrestrial (DVB-T) standard) has enhanced the performance of bidirectional communication. In this paper, the impact of using diversity techniques in such systems is investigated. In specific, the gain, obtained from utilizing this combination of adaptive MQAM and diversity techniques in the system, is also shown.

Collaborative algorithm for resource allocation in LTE-Advanced relay networks

The Capability of Relay Station deployment towards improving transmission data rates in the LTE-Advanced network has become widely accepted. However, Relay deployments are ususally burdened with the problem of resource allocation on the relay link where the relay station and users directly connected to the Donor eNB (DeNB) compete for available resources. In this paper, we propose a Collaborative Algorithm based on the Market Game theory to address this problem of Resource Allocation with LTE-Advanced Relay network. The result collated from our theoretical analysis indicates an improvement in the data rates achieved by users within the relay stations cell range.