Using UNII-3 Wi-Fi Frequencies to Establish Long Distance Point-to-Point Links

Abstract

This paper demonstrates the use of Unlicensed National Information Infrastructure (UNII-3), 5.725-5.825GHz, Wi-Fi frequencies, in the IEEE802.11a/n standard in setting up long distance point-to-point links, capable of providing broadband internet in rural areas. Although this frequency band was intended for indoor wireless local area networks, its lack of licensing and inexpensive off-shelf networking devices has prompted many researchers and technology enthusiasts to extend its use to outdoor settings. This paper presents a long distance point-to-point test-bed model that uses high-gain directional antennas that may be replicated to provide broadband internet access in rural areas particularly in developing countries. Six long-distance point-to-point links have been set up. A link distance of 24.3kilometers, the longest so far, has been achieved. An average peak throughput of 98.4Mbps has been observed on each of the six links set up, irrespective of its link length. This test-bed model is easy and inexpensive to implement and it may be replicated to provide broadband internet access in the rural areas. The paper shows that using a TDMA based Wi-Fi radio overcomes the fundamental challenges associated with the use of the off-the-shelf Wi-Fi radio whose Media access layer is based on CDMA/CA MAC protocol to implement long distance links. Further, the performance of the long distance links when the channel width is varied is analyzed. This model, therefore, validates the use of these unlicensed frequencies and proves that as long as a clear line of sight between the nodes is achievable, high bandwidth links may be achieved capable of serving one thousand or more simultaneous users each utilizing at least 100kbps.