Kaohsiung County Unified Broadband Mobile Network

Kaohsiung County Unified Broadband Mobile Network

Ran-Fun Chiu (Hewlett Packard Laboratories, USA), Yuan-Sen Yeh (Tatung InfoComm Company, Taiwan) and Chiu-hsing Yang (Kaohsiung County Government, Taiwan)
DOI: 10.4018/978-1-61520-871-5.ch009
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Since 2005, the Taiwanese government has invested over $1.2 billion into the M-Taiwan program to bolster Taiwan’s broadband mobile communications industry and modernize its IP network infrastructure. In addition to building a nation-wide IP fiber backbone and providing R&D grants for developing new technologies and novel applications, it has also co-funded the constructions of four large-scale test networks, and the Kaohsiung County unified broadband mobile network is the largest one. The network construction has three major tasks: (1) building a large scale wireless mobile network with WiMAX as the core technology and supplementing with Wi-Fi where the deployment of WiMAX is not feasible; (2) converting all telephones in the county’s government offices and schools from the conventional PSTN circuit-switched systems to VoIP to unify the two separated voice and data networks to one common IP network; and (3) deploying a host of new application services that include services promoted by the M-Taiwan program and county specific services. This chapter gives an overview of the system architecture, the employed technologies, the application services, the test results, and the challenges.
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2. Mobile Wimax Wireless Network

In 2006, the National Communications Commission (NCC) of Taiwan allocated the frequency band of 2.5 GHz to 2.69 GHz for mobile WiMAX transmission. In 2007, NCC granted three 30- MHz channels from 2.5 GHz to 2.59 GHz in an open-bid procedure to six licensees, three in northern Taiwan and three in southern Taiwan. For reducing co-channel interferences, each licensee further divided its 30 MHz channel into three equal segments, 10 MHz each. The antenna of a base station has three sectors; each sector operates in one of the frequency segments. The frequency reuse plan is shown in Figure 1.

Figure 1.

M-Taiwan mobile WiMAX frequency reuse plan

The physical layer of mobile WiMAX follows the OFDMA (Orthogonal Frequency Multiple Access) specification defined in the IEEE 802.16e-2005 standard (IEEE 802.16-2004, 2004; IEEE 802.16e-2005, 2005). It operates in a TDD (Time Division Duplex) mode; that is, the time domain of the 10MHz channel is divided into fixed-size time frame intervals in which the base station (BS) and the mobile stations (MS) transmit alternatively in time. The key time frame parameters and both the maximum downlink (from BS to MS) and the maximum uplink (from MS to BS) transmission bit rates with different levels of modulation and coding are shown in Table 1.

Table 1.
Mobile WiMAX time frame parameters and maximum DL/UL transmission rates
System bandwidth10MHz
FFT Size1024
Null Sub-Carriers184184
Pilot Sub-Carriers120280
Data Sub-Carriers720560
Symbol Period, Ts102.9 microseconds
Frame Duration5 millisecond
OFDM Symbols/Frame48
Data OFDM Symbols44
ModulationCode RateDownlink Rate, MbpsUplink Rate, Mbps
QPSK½ CTC, 6x1.060.78
½ CTC, 4x1.581.18
½ CTC, 2x3.172.35
½ CTC, 1x6.434.70
¾ CTC9.57.06
16QAM½ CTC12.679.41
¾ CTC19.0114.11
64QAM½ CTC19.0114.11
2/3 CTC25.3418.82
¾ CTC28.5121.17
5/6 CTC31.6823.52

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