Physical Cell Identifier Assignment in Dense Femtocell Deployment

In this chapter, the authors deal with a mechanism of Physical Cell Identifier (PCI) assignment for dense femtocell scenarios within LTE/LTE-Advanced networks. After describing the need for femtocells in future Self-Organizing Networks (SONs), the problem is presented. The chapter discusses background information such as related works in this research field and current assignment methods. Subsequently, challenges are defined, and two mechanisms to assign PCIs are proposed. Both the mechanisms are capable of assigning collision-free PCIs and solving any future confusion events that may occur as the network grows in terms of the number of femtocells. To evaluate the algorithms, a model is described and simulation results for two different scenarios are presented.

Access Network Selection in a 4G Environment

4G networks provide bandwidth of up to 1Gbps for a Mobile Node (MN) that is moving at pedestrian speed. On the other hand, it also supports mobile nodes that can move at a speed of 250 km/hr with bandwidths value of 100 Mbps. This sets the premise of a network that supports diverse needs. This goal will be harder to achieve if Network Selection Problems (NSP) are not addressed comprehensively. NSP refers to the selection of target access network selection from a collection of Candidate Networks (CNs) when MNs are moving from one access network into another. The most logical way of achieving this is to select the “best” network. This translates to identifying performance values of the CNs. The analysis in this chapter shows clearly that access network selection done based on limited criteria is detrimental in achieving optimum communication. Instead, this chapter suggests a framework that would be complementary to a 4G network.

MEMS-Enabled Smart Beam-Steering Antennas

In recent years, Microelectromechanical Systems (MEMS) technology has seen a rapid rate of evolution because of its great potential for advancing new products in a broad range of applications. The RF and microwave devices and components fabricated by this technology offer unsurpassed performance such as near-zero power consumption, high linearity, and cost effectiveness by batch fabrication in respect to their conventional counterparts. This chapter aims to give an in-depth overview of the most recently published methods of designing MEMS-based smart antennas. Before embarking into the different techniques of beam steering, the concept of smart antennas is introduced. Then, some fundamental concepts of MEMS technology such as micromachining technologies (bulk and surface micromachining) are briefly discussed. After that, a number of RF MEMS devices such as switches and phase shifters that have applications in beam steering antennas are introduced and their operating principals are completely explained. Finally, various configurations of MEMS-enabled beam steering antennas are discussed in detail.

Analysis of VoIP Traffic over the IEEE 802.16 Protocol

Voice over Internet Protocol (VoIP) is one of the fastest growing applications for the Internet today and is a very important service because mobile users can utilize voice services more cheaply compared with most mobile systems. A crucial application over these networks is VoIP over the Worldwide Interoperability for Microwave Access (WiMAX), which is one of the technologies in Broadband Access Networks based on IEEE 802.16 standards. It provides high throughput broadband connections over long distances, which supports Point to Multi-Point (PMP) wireless access. A hurdle, however, is the number of voice connections that can be supported. Since VoIP requires short end-to-end delays, supporting as many VoIP users as possible in a mobile broadband wireless access network, considering limited radio resources, becomes a very important issue. In this chapter, the authors use a theoretical model and an algorithm to evaluate the performance of some of the most important VoIP codecs.

Hierarchical QoS Admission Control Mechanism for IEEE 802.16j Mobile Multi-Hop Relay WiMAX Network

This chapter presents some performance issues in Worldwide Interoperability for Microwave Access (WiMAX) network and focus on the capability of non-transparent relay in Mobile Multi-Hop Relay (MMR) WiMAX Network. In this work, an admission control mechanism with hierarchy Quality of Service (QoS) is developed for the relay architecture. An open source-based simulator is used to evaluate the three types of QoS classes, which are Unsolicited Grant Access (UGS), Real Time Polling Service (rtPS), and Non-Real Time Polling Service (nrtPS). Two scenarios of non-transparent relay topologies are set up for different numbers of subscribers with different types of QoS application classes. Three performance metrics, which are bandwidth utilization, number of slots used, and number of admitted service flow, are observed and plotted in graph. The results show the hierarchy-based QoS admission control mechanism can enhance the throughput of provided services by 35% compared to the conventional method without the admission control approach.

An Optimum Routing Technique for MANET over LTE Cellular Networks

Mobile Ad Hoc Networks (MANET) is a peer-to-peer communication technique that can transmit voice or data from one mobile device to another without the support of fixed infrastructures. Multi-hop routing has improved in the last few decades, and MANET is considered one of the latest trends in modern cellular communications. Studies have been carried out to find optimum routing techniques for MANET, but the majority of the works are within IEEE 802.11 environments. Long Term Evolution (LTE) series 8, which is an IP-based architecture, can offer the added benefit of co-operative communication and reduced transfer latency. Earlier research articulated a new MANET algorithm called IP Address Associated 4-N Intelligent Routing Algorithm (IPAA4NIR), which provided fast, reliable, and energy-efficient communications. This book chapter incorporates IPAA4NIR with co-operative communications to obtain optimum routing technique for MANET using LTE cellular network. The chapter also includes the statistical analysis of the proposed algorithm and simulations using OPNET modeller. A comparison with other prominent algorithm proves the proposed algorithm can use the added features of LTE and provides an optimum communication technique for MANET devices.

Best-M Feedback Technique in 4G-LTE Systems

The feedback load is an important parameter with a large impact in Orthogonal Frequency Division Multiple Access (OFDMA) techniques, as a feedback over each one of the subcarriers will induce a non-acceptable signaling load in the system, so that some optimization and feedback reduction strategies are required to meet practical systems demands. The decision over the best strategy for feedback optimization highly depends on the number of available users in the system. The authors obtain the users’ effect on the system through a feedback strategy over a subset of the subcarriers showing the best channel conditions, where a closed form expression of the obtained data rate is formulated to exactly indicate the effect of the number of users, the operating SNR, and/or the available number of feedback bits in the system. Quality of Service (QoS) is also obtained using the Symbol Error Rate (SER). The performance of the presented scheme is compared to the one-bit feedback strategy, where interesting conclusions are obtained.

Collaborative Mobile Clusters

Future wireless communication systems are expected to offer several gigabits data rate. It can be anticipated that the advanced communication techniques can enhance the capability of mobile terminals to support high data traffic. However, aggressive technique induces high energy consumption for the circuits of terminals, which drain the batteries fast and consequently limit user experience in future wireless networks. In order to solve such a problem, a scheme called collaborative mobile cluster is foreseen as one of the potential solutions to reduce energy consumption per node in a network by exploiting collaboration within a cluster of nearby mobile terminals. This chapter provides a detailed analysis of the energy consumption of a terminal joining the cluster and also analyzes the conditions for energy savings opportunities.

Distributed Antenna Systems for Enhanced Video Transmission in LTE Public Safety Networks

In this chapter, Long Term Evolution (LTE) for public safety is investigated. Particularly, Distributed Antenna Systems (DAS) are studied, and their impact on LTE public safety networks is analyzed. Furthermore, resource allocation algorithms for the purpose of real-time video transmission, in both the Uplink (UL) and Downlink (DL) directions, are proposed, and a proportional fair scheduling algorithm, applicable in both the UL and DL directions, is presented. The proposed algorithms are compared in several scenarios with and without distributed antenna systems. In addition, Quality of Experience (QoE) metrics are used to measure the quality of the video transmissions, and joint uplink/downlink quality metrics, tailored to video transmission over public safety networks, are presented. Simulation results show large enhancements in video quality due to the application of DAS with smart resource allocation in LTE public safety networks.

Analysis of Propagation Models, Delay, and Throughput for WiMAX in Urban Environments

This chapter presents a theoretical and experimental analysis of the electromagnetic signal propagation between a base station and a subscriber station in an urban setting using the IEEE 802.16d standard and test bed results, which are then compared to Ergeg’s (1998) modified version of the Hata-Okomura (1980) mathematical propagation model. The experimental results of the measurements are similar to the model using the type terrain Category B (Suburban). Additionally, under experimental conditions, equipment with technology IEEE 802.16d and IEEE 802.16e were used to analyze delay and throughput while data, voice, and video was transmitted. The tests show that delay is acceptable for Fixed WiMAX, although it is barely adequate for Mobile WiMAX. As far as throughput is concerned, the average rate is adequate to support applications that include data, voice, and video.