A comparison of wi-fi and wimax with case studies - Florida State ...
A comparison of wi-fi and wimax with case studies - Florida State ...
A comparison of wi-fi and wimax with case studies - Florida State ...
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Figure 5-17 WiBro Features<br />
The data rate <strong>of</strong> Wibro is asymmetric, for a RAS (Radio Access Station) the maximum<br />
downlink speed is 18 Mbps <strong>and</strong> uplink speed is 6 Mbps; for a PSS (Portable Subscriber Station)<br />
the maximum downlink speed is 3 Mbps <strong>and</strong> uplink speed is 1 Mbps. Under mobile conditions,<br />
WiBro can only support under 60 kmph movement. It is lower than 3G which is support at least<br />
120 kmph, but much better than Wi-Fi. The coverage <strong>of</strong> a RAS is de<strong>fi</strong>ned in three levels, Pico,<br />
Micro <strong>and</strong> Macro. Pico can cover a radius <strong>of</strong>100 meters area. Coverage <strong>of</strong> Micro is 400 meters<br />
<strong>and</strong> Macro is 100 meters. This design would make installation <strong>of</strong> RAS more flexible. [79] – [82]<br />
WiBro also has QoS. It contains three schemes, rtPS, nrtPS <strong>and</strong> BS; not including UGS. For<br />
saving power, WiBro provides sleep mode for end users to extend the battery life. In order to<br />
improve the system performance, WiBro introduces scheduling algorithm for transmission<br />
service <strong>and</strong> AMC for coding <strong>and</strong> modulation. WiBro also supports ARQ/H-ARQ (Hybrid<br />
Automatic Request) as well as WiMax. This scheme can effectively re-send the packet, if it is<br />
damaged by interference or channel fading. The h<strong>and</strong><strong>of</strong>f break time between two RASs is less<br />
than 150 ms, it is a very good performance comparing <strong>wi</strong>th other <strong>wi</strong>reless algorithm, such as<br />
PHS. [79] – [82]<br />
There are still other optional technologies used in WiBro, for example MIMO, AAS <strong>and</strong><br />
SDCA(Space Time Coding Adoption). The purpose is to extend the coverage <strong>and</strong> against<br />
interference. Table 5-8[79] – [82] contains the PHY speci<strong>fi</strong>cation <strong>of</strong> WiBro. Figure 5-18[79] –<br />
[82] shows the MAC-layer structure.<br />
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