| 摘要(英) |
The latest standard of Wi-Fi technology, IEEE 802.11n, has greater wireless transmission bandwidth, broader transmission coverage and even more reliability than 802.11g and 802.11a. The data transmitting rate can reach six times which higher than the capacity of 802.11g and 802.11a. IEEE 802.11n utilizes MIMO (Multi-Input Multi-Output) as its core technology using multiple antennas to send and receive signals, which increases not only signal capability but overall network-capacity by using more channels. The experimental results show that significant improvement on both signal strength and signal stability. Therefore, the PHY (Physical layer) transmission bandwidth of 802.11n can reach up to 600MHz, which strengthens MAC (Media Access Control layer) enhancement and frame aggregation. Consequently, it is capable of supporting 2.4 and 5GHz dual-band network and 20/40 MHz bandwidth as well. Furthermore, it is compatible with the current specification of 802.11a/b/g.
In this thesis, we choose the most four popular 802.11n APs (Access Point) and Stations from the market, and then evaluate their performance under infrastructure mode. According to out experimental results, we will identify the combinations of the most reliable and efficient chip which are available in the market. In addition, some experiments are performed based on the protocols of latest IEEE draft standard such as (1) working on the Greenfield and the Mixed mode, (2) the differences of 20 MHz/40MHz bandwidth, and (3) the effect of other band interference working on the same bandwidth. These experimental results are analyzed and discussed in depth. Otherwise, in order to set up the experimental environment, the modes of 802.11n and 802.11g are used at the same indoor environment with two different restrictions: the different antennas and the same types of bands. We also do some experiment that we set up some different access points in the environments of blockage, paths with multiple crossroads and various distances. According to our experimental results, we confirm that using multiple antennas the transmission can become faster and provide better coverage area. |
| 參考文獻 |
[1] IEEE Std 802.11b-1999, Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications: Higher-Speed Physical Layer Extension in the 2.4 GHz Band.
[2] IEEE Std 802.11a-1999, Part11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications: High-Speed Physical Layer in the 5 GHz Band.
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