3GPP Broadband Evolution to IMT-Advanced - 4G Americas

There are also a number of planned improvements for CDMA2000 1xRTT in a versionreferred to as 1x-Advanced that will significantly increase voice capacity, doubling it if allenhancements are implemented. CDMA operators are not only considering 1x-Advancedas a means to increase voice capacity, but as a means to free up spectrum to supportmore data services, such as deploying more EV-DO carriers or deploying LTE.3GPP2 has defined technical means to integrate CDMA2000 networks with LTE along twoavailable approaches:1. Loose coupling. This involves little or no inter-system functionality, and resourcesare released in the source system prior to handover execution.2. Tight coupling. The two systems intercommunicate with network-controlled makebefore-breakhandovers. Tight coupling allows maintenance of data sessions withthe same IP address. This will likely involve a more complex implementation thanloose coupling.CDMA2000 is clearly a viable and effective wireless technology and, to its credit, many ofits innovations have been brought to market ahead of competing technologies.WiMAXWiMAX has emerged as a potential alternative to cellular technology for wide-areawireless networks. Based on OFDMA and recently accepted by the ITU as an IMT-2000(3G technology) under the name OFDMA TDD Wireless Metropolitan Area Network(WMAN), WiMAX is trying to challenge existing wireless technologies—promising greatercapabilities and greater efficiencies than alternative approaches such as HSPA. But asWiMAX, particularly mobile WiMAX, has come closer to reality, vendors have continued toenhance HSPA and perceived WiMAX advantages are no longer apparent. Moreover, LTEnetworks are now beginning to be deployed.Instead, WiMAX has gained the greatest traction in developing countries as an alternativeto wireline deployment. In the United States, Clearwire, Sprint Nextel and others (Intel,Google, Comcast, Time Warner Cable, and Bright House Networks) have created a jointventure to deploy a nationwide WiMAX network. In July 2010, this network was availablein 44 markets across the U.S. 38The original specification, IEEE 802.16, was completed in 2001 and intended primarily fortelecom backhaul applications in point-to-point, line-of-sight configurations usingspectrum above 10 GHz. This original version of IEEE 802.16 uses a radio interface basedon a single-carrier waveform.The next major step in the evolution of IEEE 802.16 occurred in 2004 with the release ofthe IEEE 802.16-2004 standard. It added multiple radio interfaces, including one basedon OFDM-256 and one based on OFDMA. IEEE 802.16-2004 also supports point-tomultipointcommunications, sub-10 GHz operation, and non-line-of-sightcommunications. Like the original version of the standard, operation is fixed, meaningthat subscriber stations are typically immobile. Potential applications include wirelessInternet Service Provider (ISP) service and local telephony bypass (as an alternative tocable modem or DSL service). Vendors can design equipment for either licensed orunlicensed bands.38 Source: Clearwire Press Release, “Clearwire Brings CLEAR 4G to Merced and Visalia, California,” July1, 2010.Transition to 4G: 3GPP Broadband Evolution to IMT-Advanced, Rysavy Research/3G Americas, Aug 2010 Page 36