Computer And Technologies

Computer And Technologies: Mobile WiMAX Technology and Application in Industry..

Wednesday, 22 April 2009

Mobile WiMAX Technology and Application in Industry..

I will describe something about WiMAX application in industry and provide some analysis on WiMAX application progress. This part will also give some advantages and challenges for mobile WiMAX .There are mainly 3 aspects: the 3G license is till not distributed; it is harder to find the spectrum for mobile WiMAX than fixed WiMAX; the technology selection may effect the whole development of Telecommunication field in China.
  • WiMAX standard series:
IEEE802.16 is also called IEEE Wireless MAN air interface standard, which works between 2~66GHz wireless spectrum. Because the provided wireless system coverage can reach as large as 50km, so 802.16 is mainly used in Metropolitan Area Network (MAN). Based on whether mobility is supported or not, 802.16 standard can be devided into fixed and mobile broadband wireless access airlink.
After the publish of 802.16e standard, the Mobile Multi-hop Relay task group of 802.16j became one of the groups with most participation in IEEE 802.16. Through mobile multi-hop relay technique, it can increase the transmission rate, extent coverage range, and achieve obtaining uniform data rate property for users in the coverage. This property is quite likely to fulfill the requirements of future 4G mobile communication technology. While IEEE 802.16 MMR SG is the only organization which puts this technique into standard. This attracts a lot of industry companies to join in and participate and it also became a new direction in 802.16 standard.
The signal of wireless network base station has shadow fading effect because of the coverage area. This makes the effective coverage shrink a lot. In order to make sure the the user signal is still continuous when there is serious shadow fading, signal relay is used to solve the problem.
The advantages of mobile multi-hop relay:
  • Low cost: relay station doesn't need the support of wired-line backhaul which reduces the cost of building backhaul network greatly. And the complexity and cost of relay station is much lower than base station. So although the effect provided may not be as good as adding a cell, it is still very attractive to operator for its low cost and flexibility.
  • Selective power amplification: Different from the traditional analog power amplifier to amplify all the received signal, relay station will make digital process for received signal and amplify the power depending on situation. Furthermore, because when the relay station receives the signals, the interfering signals have already been dealt with. So when relaying signals, all the power on the signals needed to be relayed. While the signals don't need to be relayed, interfering signals will not be relayed as well.
  • Multi-hop increasing coverage area: many neighboring relay staions can relay signals to farther away areas.

Relay task group has decided that this standard should be realized under the condition without modifying mobile station. Then the mobile station may not be able to recoganize the existance of relay staion. This is also one of the difficulties.

Mobile WiMAX production speeds up:

WiMAX forum plays an important role in WiMAX market. The approval of this forum and other work decide the possible future development and application of WiMAX. Nowadays the main work has totally moved to wireless WiMAX and speeds up to put technology in market. The time of approval and whether it is successful has relation with when the WiMAX devices will be on the market.

The approval of fixed WiMAX devices has started from the beginning of 2006. While because the approval of mobile WiMAX was postponed, it can only start at the end of 2006.

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