CHAPTER 15 Wide-Area Wireless Networks (WANs) — GSM Evolution 15.1 Introduction
Third-generation (3G) wireless systems [2,3,9] offer access to services anywhere from a single terminal; the old boundaries between telephony, information, and entertainment services are disappearing. Mobility is built into many of the services currently considered as ﬁxed, especially in such areas as high speed access to the Internet, entertainment, information, and electronic commerce (e-commerce) services. The distinction between the range of services offered via wireline or wireless is becoming less and less clear and, as the evolution toward 3G mobile services speeds up, these distinctions will disappear in the ﬁrst decade of the new millennium. Applications for a 3G wireless network range from simple voice-only communications to simultaneous video, data, voice, and other multimedia applications. One of the main beneﬁts of 3G is that it allows a broad range of wireless services to be provided efﬁciently to many different users. Packet-based Internet Protocol (IP) technology is at the core of the 3G services. Users have continuous access to on-line information. E-mail messages arrive at hand-held terminals nearly instantaneously and business users are able to stay permanently connected to the company intranet. Wireless users are able to make video conference calls to the ofﬁce and surf the Internet simultaneously, or play computer games interactively with friends in other locations. Figure 15.1 shows the data rate requirement for various services. In 1997, the TIA/EIA IS-136 community through the Universal Wireless Consortium (UWC) and the Telecommunications Industry Association (TIA) TR 45.3 adopted a three-part strategy for evolving its IS-136 TDMA-based networks to 3G wireless networks to satisfy International Mobile Telephony-2000 (IMT-2000) requirements. The strategy consists of: • Enhancing the voice and data capabilities of the existing 30 kHz carrier (IS-136 ) • Adding a 200 kHz carrier for high-speed data (384 kbps) in high mobility applications • Introducing a 1.6 MHz carrier for very high-speed data (2 Mbps) in low-mobility applications 469
Wide-Area Wireless Networks (WANs) — GSM Evolution
Bits per second Video (High Quality); (Medium Quality); (Slow Scan)
1M 100 k 10 k Voice 1k Images, Audio, Text
Service Figure 15.1 User data requirements.
The highlight of UWC strategy was the global convergence of IS-136 time division multiple access (TDMA) with a global system for mobile communications (GSM) through the evolution of the 200 kHz GSM carrier for supporting high-speed data applications (384 kbps) while also improving a 30 kHz carrier for voice and mid-speed data applications. In this chapter we focus ﬁrst on GSM evolution to packet data services and present the details of the general packet radio service (GPRS) and the enhanced data for GSM evolution (EDGE) service. We then provide details of 3G systems including wideband code division multiple access (CDMA) (WCDMA) (i.e., universal mobile telecommunications services (UMTS)). We conclude the chapter by outlining the details of high-speed downlink packet access (HSDPA).
GSM Evolution for Data
From a radio access perspective, adding 3G capabilities to 2G systems mainly means supporting higher data rates. Possible scenarios depend on spectrum availability for the network service provider. Depending on the spectrum situation, two different migration paths can be supported: • Reframing of existing spectrum bands • New or modiﬁed spectrum bands
Two 3G radio access schemes are identiﬁed to support the different spectrum scenarios: 1. Enhanced data rates for GSM evolution (EDGE) with high-level modulation in a 200 kHz TDMA channel is based on plug-in transceiver equipment, thereby allowing the migration of existing bands in small spectrum segments. 2. Universal mobile telecommunications services (UMTS) is a new radio access network based...
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