Security and Mobility Aspects of Femtocell Networks

This chapter discusses security and mobility aspects of femtocell networks, given protocol level descriptions in the subsections. The connectivity between FAP and core network has a high risk of being compromised. The chapter discusses how Host Identity Protocol (HIP) can be adapted in femtocell technology to improve security and mobility issues. This chapter presents several enhancements to the femtocell technology such as strong authentication, service registration, identity verification, and node multihoming. In addition, Encapsulating Security Payload (ESP) is used to provide confidentiality, data origin authentication, connectionless integrity, anti-replay service, and limited traffic flow confidentiality. Furthermore, enhanced mobility support by means of locator/identity separation and node multihoming is discussed in the scope of 3GPP femtocells.

Multiple Frequency Offsets Compensation in OFDMA Femtocells

With the properties of interference avoidance and the robustness against multipath channels, Orthogonal Frequency Division Multiple Access (OFDMA) has been considered a promising solution to the interference control problem in femtocells. As a multi-carrier transmission technique, OFDMA, however, is highly vulnerable to the Carrier Frequency Offset (CFO). This chapter discusses the challenges of multiple frequency offsets compensation in OFDMA femtocells. A number of multiple frequency offsets compensation algorithms are reviewed and their complexities are discussed in detail. A new approach that exploits the redundancy offered by cyclic prefix is then introduced to enhance the compensation performance. Finally, numerical results are presented to illustrate the performance of different compensation algorithms.

Spectrum Handover Strategies for Cognitive Femtocell Networks

Cognitive femtocell is a promising technology for the next generation wireless networks to improve the efficiency of spectrum utilization, coverage, and to attain higher data rates for indoor communications. In this chapter, the new Cognitive Femtocell Switching Unit (CFSU) is proposed to support handover management for 10-20 cognitive femtocells as a local geographical cluster. Thus, CFSU acts as a service coordinator between femtocells and macrocell areas to improve spectrum utilization and coexistence. Then, the chapter presents solutions for spectrum handover to achieve guaranteed quality of radio service, spectrum utilization, and enable an excellent local handover management to reduce unnecessary handovers between femtocell base stations. The challenges and solutions that are presented in this chapter have the ability to maintain services by evaluating the requested quality of services.

The Comparison between WLAN and Femtocell

The communication link of femtocell may be one of Wide Area Network (WAN) technologies, such as, Asymmetric Digital Subscriber Line (ADSL). Femtocell used a public network to establish connectivity between femtocell and core network elements where there are a set of challenges to the operators. However, femtocells use IP Network as a backhaul architecture instead of conventional cellular network infrastructure, so that Femtocells and WiFi infrastructure networks can come to a compromise as they have a lot of common iterative and inter-related technologies and activities. This raises the question as to whether femtocell technology will substitute the existing WiFi technology. By carefully analyzing the similarities and differences between the two technologies one can find this answer. This chapter provides a technical comparison between Femtocells and WiFi in terms of architecture, operation, and standards.

Femtocells for Public Safety Communications

The increased adoption of rich multimedia solutions in public safety communications is enhancing information sharing for improved situational awareness as well as boosting operational efficiency. However, the aforementioned benefits also place increasingly stringent quality-of-service demands on the underlying network infrastructure. In this chapter, the authors review the added value of utilizing femtocells for various public safety communications scenarios. To that end, a detailed case study on the exploitation of femtocellular resources for emergency telemedicine applications is presented as an illustrative example. Simulations carried out for an Long Term Evolution (LTE) network environment demonstrate significant improvements in terms of achievable throughput for the emergency response personnel when access to subscriber-owned residential LTE Home eNode Bs available in the indoor emergency sites is allowed, compared to the conventional option of accessing only operator-owned macro eNode Bs.

LTE Femtocells

The growing interest in the possible deployment of mobile cellular networks in the 790-862 MHz frequency band, resulting from the transition process from analogue to digital TV, will pave the way for cutting-edge technology (LTE) and a new interesting market.

Worldwide Standardizations of Femtocell

This chapter addresses global 3G/4G femtocell standardization activities in 3GPP, 3GPP2 and the WiMAX Forum®1, as well as related activity in the Broadband Forum (BBF) and Femto Forum. Common challenges introduced by femtocell technology are identified, as well as the reasons for pursuing standardized solutions and why the various standards bodies diverged in their approaches. A brief overview of each group is given (e.g., the Technical Specification Groups and/or Working Groups in which femtocell-related discussions take place). This is followed by a detailed review of the femtocell architecture devised for each radio access technology, including the network elements, interfaces, and protocols that were created or revised to support femtocells, and a summary of the femtocell-related documents published by each group. Finally, brief descriptions of the supporting role played by both the BBF and Femto Forum are given.

Handover Procedure in Femtocells

Implementation of small base stations, known as femtocells, increases the throughput of indoor as well as outdoor users. However it brings several issues that need to be addressed. This chapter is focused on mobility management and problems closely related to the handover procedure. The main challenge is to guarantee efficient handover from/to/between femtocells. It means to ensure minimum signaling overhead due to unnecessary handovers, to minimize handover interruption, and to mitigate interference caused by elimination of redundant handovers. The basic principle of the handover is explained together with the main challenges concerning the handover in a scenario with deployed femtocells. Furthermore, individual issues are described in detail and possible ways to solve them are contemplated. The chapter does not stick to any specific standard; however, it is focused on the general principles and problems of the handover procedure from the femtocell’s point of view.

Interference Mitigation in Femtocell using Optimized Power Control

The femtocell network is a new technology that uses the advantage of an Internet backbone to enhance the cellular coverage in residential or small business areas. However, due to the expected random deployment of the Femtocell Access Point (FAP), there is a strong probability of interference among the femtocell nodes and between the femtocells and the macrocell nodes. In this chapter, an interference enhancement for OFDMA systems is developed and designed for two tiered macro-femtocell networks. An adaptive power control is calculated based on selecting the minimum interference channel with the optimized channel gain. In the simulation a number of the FAPs, the distance between the macrocell and the femtocell, and the path loss between the macrocell node and the FAPs are used as design parameters. By using optimized power control performance enhancement the interference degradation ratio can be observed.

Introduction to Femtocell

Femtocell is a licensed indoor coverage solution served by a residential licensed access point known as FAP or Home node B. Femtocell promises to address the cost and coverage issues of mobile networks and increase cellular network capacity by rising above the impact of wall attenuation on macrocell deployment. The Femto Forum defines femtocell as a low cost access point leveraged on mature mobile technology that operates on a licensed spectrum and utilizes broadband (IP) as backhaul. This chapter gives an overview of the femtocell technology and architecture, standard and business models.