Sassan Ahmadi

An overview of next-generation mobile WiMAX technology

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+.

On the architecture, operation, and applications of VMR-WB: the new cdma2000 wideband speech coding standard

This article is an overview of the architecture and operation of the VMR-WB5 a source- and network-controlled variable-rate multimode codec designed for robust processing of wideband speech. To enable a smooth transition from legacy narrowband voice services, VMR-WB is also capable of processing conventional telephone-bandwidth speech. The VMR-WB codec is interoperable with AMR-WB at certain bit rates, thus eliminating quality degradation and additional delay due to transcoding

An Overview of 3GPP Long-Term Evolution Radio Access Network

The growing demand for mobile Internet and wireless multimedia applications such as Internet browsing, interactive gaming, mobile TV, video and audio streaming has motivated development of broadband wireless access technologies in recent years. As a result, the 3rd Generation Partnership Project (3GPP) initiated the work on the long-term evolution (LTE) in late 2004. LTE will ensure 3GPPs competitive edge over other cellular technologies. The evolved UMTS terrestrial radio access network (E-UTRAN) substantially improves end-user throughputs, sector capacity and reduces user-plane and control-plane latencies, bringing significantly improved user experience with full mobility. With the emergence of Internet Protocol (IP) as the protocol of choice for carrying all types of traffic, LTE is expected to provide support for IP-based traffic with end-to-end quality of service (QoS). Voice traffic will be supported mainly as voice over IP (VoIP) enabling better integration with other multimedia services. Initial deployments of LTE are expected by 2010 and commercial availability on a larger scale will likely happen a few years later. Unlike its predecessors, which were developed within the framework of Release 99 UMTS architecture, 3GPP has specified the evolved packet core (EPC) architecture to support the E-UTRAN through reduction in the number of network elements and simplification of functionality but most importantly allowing for connections and handover to other fixed and wireless access technologies, providing the network operators the ability to deliver a seamless mobility experience. 3GPP has set aggressive performance requirements for LTE that rely on improved physical layer technologies such as orthogonal frequency division multiplexing (OFDM) and single-user and/or multi-user multiple-input multiple-output (MIMO) techniques,