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Shrinking cell sizes, primarily a result of keeping up with the increasing demand for higher data rates, are stretching thin the notion of our traditional cellular system architecture. More and more base stations are serving smaller and smaller areas (cells) which in effect is driving up deployment costs. The option of deploying relay stations is increasingly beginning to look like a solution to the problem of providing a cost-effective way to extend the coverage and capacity in a cellular network. A relay station can be used to extend the point-to-multipoint link between the base station and mobile stations. Relay stations connect to the base stations without wires and are expected to be deployed to cover smaller geographic areas. Primarily the deployment costs but also the equipment costs are expected to be substantially lower than those of base stations. In this article we first introduce the relay station and discuss the place it is likely to carve out for itself in the traditional cellular architecture. We highlight the important economic and performance benefits relay stations could potentially offer, and outline a few scenarios where relays are likely to be deployed in the beginning. The multihop relay standard developed by the IEEE 802.16 working group is then used as a basis to provide an overview of the relay-enhanced cellular architecture and the key choices that can be made in developing relay support within a cellular system - a precursor to what can be expected in later releases of the Mobile WiMAX system. Finally, we discuss some future directions in the development of relay systems. [ABSTRACT FROM AUTHOR]

The growing demand for wireless Internet services is accelerating the evolution of wireless networks toward all-IP architecture, and the mobile WiMAX network is a prominent example. Although currently deployed mobile WiMAX networks use hierarchical architecture, flat architecture is feasible and specified as a design alternative in the mobile WiMAX standard. In flat architecture the functionalities of the ASN-GW and BS are consolidated into a single element. In this article we first discuss the benefits and challenges of flat architecture mobile WiMAX networks. We then present a scheme to deal with the seamless mobility issue, which is one of the key challenges of the flat architecture. The proposed scheme combines two standard IP-mobility protocols, Proxy Mobile IP and Fast Mobile IP, and customizes them for IEEE 802.16e-based mobile WiMAX networks. This provides interoperability with existing mobile WiMAX networks. We demonstrate the viability of the proposed scheme through simulations using NS-2. [ABSTRACT FROM AUTHOR]

The growing demand for mobile Internet and wireless multimedia applications has motivated the development of broadband wireless-access technologies in recent years. Mobile WiMAX has enabled convergence of mobile and fixed broadband networks through a common wide-area radio-access technology and flexible network architecture. Since January 2007, the IEEE 802.16 Working Group has been developing a new amendment of the IEEE 802.16 standard (i.e., IEEE 802.16m) as an advanced air interface to meet the requirements of ITU-R/IMT-advanced for 4G systems, as well as for the next-generation mobile network operators. Depending on the available bandwidth and multi-antenna mode, the next-generation mobile WiMAX will be capable of over-the-air data-transfer rates in excess of 1 Gb/s and of supporting a wide range of high-quality and high-capacity IP-based services and applications while maintaining full backward compatibility with the existing mobile WiMAX systems to preserve investments and continuing to support first-generation products. This tutorial describes the prominent technical features of IEEE 802.16m and the potential for successful deployment of the next generation of mobile WiMAX in 2011+. [ABSTRACT FROM AUTHOR]

To support fast and efficient handovers in mobile WIMAX, we propose Fast Intra-Network and Cross-layer Handover (FINCH) for intradomain (intra-CSN) mobility management. FINCH is a complementary protocol to Mobile IP (MIP), which deals with interdomain (inter-CSN) mobility management in mobile WiMAX. FINCH can reduce not only the handover latency but also the end-to- end latency for MIP. Paging extension for FINCH is also proposed to enhance the energy efficiency. The proposed FINCH is especially suitable for real-time services in frequent handover environment, which is important for future mobile WiMAX networks. In addition, FINCH is a generic protocol for other IEEE 802-series standards. This is especially beneficial for the integration of heterogeneous networks, for instance, the integration of WiMAX and WiFi networks. Both mathematical analysis and simulation are developed to analyze and compare the performance of FINCH with other protocols. The results show that FINCH can support fast and efficient link layer and intradomain handovers. The numerical results can also be used to select proper network configurations. [ABSTRACT FROM AUTHOR]

The IEEE 802.16e World Interoperability for Microwave Access (WiMax) system plays an important role in the future wireless metropolilan area network (WMAN). Orthogonal frequency division multiple access (OFDMA), adopted in the IEEE 802.16e WiMax system, has many advantages in the physical layer and also poses many challenges for radio resource allocation. One of interesting radio resource allocation issue in the OFDMA system is to partition the overall radio resource (bandwidth and time duration) into two portions: one for random access and the other for connection-oriented access. In the IEEE 802.16e WiMax system, a truncated binary back-off algorithm is adopted to resolve the contention in random access, while the time-division OFDMA is used for the connection-oriented access. The main contribution of this paper is to design an analytical approach to determine the optimal amount of reserved radio resource in both time and frequency domains for random access, with the objective of maximizing the overall efficiency of radio resource while satisfying the delay requirements for supporting real-time services. Furthermore, an analytical model for calculating the access latency and the efficiency of the reserved radio resources is developed. [ABSTRACT FROM AUTHOR]

We propose a methodology to evaluate the Voice- over-IP (VoIP) capacity and performance of orthogonal frequency-division multiple-access (OFDMA).based systems. The approach combines the queuing and interference analyses to find the delay and power outage. Using this analytical framework, we provide insight into tradeoffs among capacity-limiting factors, including channel dimensions, power, interference threshold and latency, and we identify techniques for capacity optimization. The numerical demonstrations are carried out on the newly standardized Ultra Mobile Broadband (UMB) system. The same methodology can also be applied to Universal Mobile Telecommunications System (UMTS) Long Term Evolution (LTE) and wireless mobile Worldwide Interoperability for Microwave Access (WiMAX) systems. [ABSTRACT FROM AUTHOR]

Ethernet services represent a steadily growing portion of the fixed telecommunication market. To enable the provisioning of Ethernet services over IEEE 802.16e, the Mobile WiMAX network artchitecture supports transparent Ethernet transport as an optional extension to the IP services architecture. Ethernet support is tightly aligned to the IP services network model, and leverages many data path and control plane functions from its IP sibling to keep the implementation and operation overhead low for the Ethernet extension. Mobile WiMAX provides IP services as well as Ethernet services over the same mobile access network. The intrinsic mobility support may create new deployment opportunities for Ethernet services. Initially, the Ethernet extension may be mostly used to realize wireless access for DSL networks based on the same network interfaces defined for the wired Ethernet-based DSL aggregation. [ABSTRACT FROM AUTHOR]

As the wireless industry makes its way to the next generation of mobile systems, it is important to engineer solutions that enable seamless integration of emerging 4G access technologies within the currently deployed and/or evolved 2G/30 infrastructures. In this article we address a specific case of such a seamless integration, that of mobile WiMAX in evolved 3GPP networks. In this context we investigate the architecture and the key procedures that enable this integration, and we also introduce a novel handover mechanism that enables seamless mobility between mobile WiMAX and legacy 3GPP access, such as UTRAN or GERAN. The core characteristic of this novel handover mechanism is that mobile terminals do not need to support simultaneous transmission on both WiMAX and 3GPP accesses; therefore, it mitigates the RF coexistence issues that exist otherwise and improves handover performance. In addition, we provide a brief overview of mobile WiMAX and the evolved 3GPP network technologies, and we set the appropriate background material before presenting our proposed handover mechanism. Our main conclusion is that integrating mobile WiMAX in evolved 3GPP networks is a compelling approach for providing wireless broad- band services, and mobility across WiMAX and 3GPP access can become seamless and efficient with no need for mobile terminals to support simultaneous transmission on both types of access. [ABSTRACT FROM AUTHOR]

Femtocells are viewed as a promising option for mobile operators to improve coverage and provide high-data-rate services in a cost-effective manner. The idea is to overlay low-power and low-cost base station devices, Femto-APs, on the existing cellular network, where each Femto-AP provides high-speed wireless connection to subscribers within a small range. In particular, Femto-APs can be used to serve indoor users, resulting in a powerful solution for ubiquitous indoor and outdoor coverage, using a single access technology such as WiMAX. In this article we consider a WiMAX network deploying both macro BSs and Femto-APs, where it is assumed that Femto-APs have wired backhaul such as cable or DSL and operate on the same frequency band as macro BSs. Simulation results show that significant areal capacity (throughput per unit area) gain can be achieved via intense spatial reuse of the wireless spectrum. In addition, Femto-APs improve indoor coverage, where the macro BS signal may be weak. Motivated by the gains in capacity and coverage offered by femtocells, we review the state of the art of this "infant" technology, including use cases and network deployment scenarios, technical challenges that need to be addressed, and current standardization and industry activity. [ABSTRACT FROM AUTHOR]

Mobile WiMAX was successfully adopted by ITU as one of the IMT-2000 technologies in November 2007. Since then mobile WiMAX (a.k.a. IP-OFDMA) has officially become a major global cellular wireless standard along with 3GPP UMTS/HSPA and 3GPP2 CDMA/EVDO. Mobile WiMAX is an OFDM-based technology available for deployment today, and new WIMAX devices come to market at much reduced cost than that of current 3G solutions. Currently over 260 service providers are deploying fixed, portable and mobile WiMAX networks in 110 countries. This article provides an overview of the mobile WiMAX system and its performance under various configurations, channel conditions, and types of data traffic. Furthermore, the article provides an overview of mobile WiMAX evolution. [ABSTRACT FROM AUTHOR]

The article presents a study on video performance on real 3G networks in consideration to fixed networks, and propose video profiles for delivering enough perceptual quality to remote users. It notes discussions which analyze video performance and response to camera remote control over Transmission Control Protocol (TCP) and User Data Protocol (UDP) and presents the use of an actual 3G network. It further notes that future work which succeeds the study will be conducted on other networks, such as the Mobile WiMax.