high-speed portable Internet), which was backed by SK Telecom and KT Corp. However, HPi was incompatible with the growing WiMax standard and was a barrier to non-Korean developers and manu- facturers. This led to its replacement by the more compatible WiBro standard. ETRI is focusing on both WiBro and a companion technology, DMB (which is described later in this chapter). According to Korea's Ministry of Information and Communication (MIC), WiBro is intended as an evolutionary technology. It will start slowly SO as to not compete immediately with 3G systems. Several years after the arrival of WiBro, MIC projects 10 million WiBro subscribers. There are already several major chipsets available for it. The use of licensed spectrum is one of the key differentiators between the U.S. WiMax technology and WiBro: In February 2002, the Korean government allo- cated 100MHz of spectrum in the 2.3GHz band, and in late 2004, WiBro Phase 1 was standardized by the Telecommunications Technology Association (TTA) of Korea. The advantage of using licensed spectrum is that it eliminates the problem of any potential interference from other sources using the same spectrum. On the other hand, WiBro's use of licensed spectrum that may not be available across the globe, along with its proprietary nature, may prevent it from becoming an interna- tional standard. These two characteristics of WiBro also lead to exacting require- ments in terms of equipment design and spectrum use. On the other hand, WiMax leaves much of the equipment design up to the equipment provider, while provid- ing enough detail to ensure interoperability between designs. WiBro base stations will offer an aggregate data throughput of 30Mbps to 50Mbps and cover a radius of 0.5 to 3 miles (1 to 5 km). Portable Internet usage can be supported for a user who is within range of a base station. WiBro also provides for QoS, SO it can reliably stream video content and other loss- and delay-sensitive data. WiBro is very similar to 802.16e (Mobile WiMax), and it allows users t