Maximising the Utility of Enterprise Millimetre-Wave Networks

Millimetre-wave (mmWave) technology is a promising candidate for meeting the intensifying demand for ultra fast wireless connectivity, especially in high-end enterprise networks. Very narrow beam forming is mandatory to mitigate the severe attenuation specific to the extremely high frequency (EHF) bands exploited. Simultaneously, this greatly reduces interference, but generates problematic communication blockages. As a consequence, client association control and scheduling in scenarios with densely deployed mmWave access points become particularly challenging, while policies designed for traditional wireless networks remain inappropriate. In this paper we formulate and solve these tasks as utility maximisation problems under different traffic regimes, for the first time in the mmWave context. We specify a set of low-complexity algorithms that capture distinctive terminal deafness and user demand constraints, while providing near-optimal client associations and airtime allocations, despite the problems' inherent NP-completeness. To evaluate our solutions, we develop an NS-3 implementation of the IEEE 802.11ad protocol, which we construct upon preliminary 60GHz channel measurements. Simulation results demonstrate that our schemes provide up to 60% higher throughput as compared to the commonly used signal strength based association policy for mmWave networks, and outperform recently proposed load-balancing oriented solutions, as we accommodate the demand of 33% more clients in both static and mobile scenarios.Comment: 22 pages, 12 figures, accepted for publication in Computer Communication

Enabling rural broadband via TV "white space"

The use of multiple frequency bands within a wireless network allows the advantages of each band to be exploited. In this paper we discuss how HopScotch, a rural wireless broadband access test bed running in the Scottish Highlands and Islands, uses both 5 GHz and ultra high frequency "white space" bands to offer large data rates and expansive coverage whilst reducing the number of base stations or required transmission power. This reduction in energy consumption allows HopScotch to provide a low-cost and green solution for rural broadband delivery

Measuring the reliability of 802.11 WiFi networks [forthcoming]

Over half of the transmission time in WiFi networks is dedicated to ensuring that errors are corrected or detected. Despite these mechanisms, many studies have concluded that frame error rates vary. An increased understanding of why frames are lost is a pragmatic approach to improving real world 802.11 throughput. The potential beneficiaries of this research, include rate control algorithms, Modulation and Coding Schemes, simulation models, frame size selection and 802.11 configuration guidelines. This paper presents a measurement study of the factors which correlate with packet loss in 802.11 WiFi. Both passive and active approaches were used to investigate how the frame size, modulation and coding scheme and airtime effect the loss rate. Overall, packet errors were high, but the size of frames were not a major determinant of the loss rate. The loss rate decreased with the airtime but at substantially lower rates than those suggested in simple packet error models. Future work will further try to isolate and investigate specific errors, such as head on collisions in the preamble

Measuring the reliability of 802.11 WiFi networks

Over half of the transmission time in WiFi networks is dedicated to ensuring that errors are corrected or detected. Despite these mechanisms, many studies have concluded that frame error rates vary. An increased understanding of why frames are lost is a pragmatic approach to improving real world 802.11 throughput. The potential beneficiaries of this research, include rate control algorithms, Modulation and Coding Schemes, simulation models, frame size selection and 802.11 configuration guidelines. This paper presents a measurement study of the factors which correlate with packet loss in 802.11 WiFi. Both passive and active approaches were used to investigate how the frame size, modulation and coding scheme and airtime effect the loss rate. Overall, packet errors were high, but the size of frames were not a major determinant of the loss rate. The loss rate decreased with the airtime but at substantially lower rates than those suggested in simple packet error models. Future work will further try to isolate and investigate specific errors, such as head on collisions in the preamble

HopScotch - a low-power renewable energy base station network for rural broadband access

The provision of adequate broadband access to communities in sparsely populated rural areas has in the past been severely restricted. In this paper, we present a wireless broadband access test bed running in the Scottish Highlands and Islands which is based on a relay network of low-power base stations. Base stations are powered by a combination of renewable sources creating a low cost and scalable solution suitable for community ownership. The use of the 5~GHz bands allows the network to offer large data rates and the testing of ultra high frequency ``white space'' bands allow expansive coverage whilst reducing the number of base stations or required transmission power. We argue that the reliance on renewable power and the intelligent use of frequency bands makes this approach an economic green radio technology which can address the problem of rural broadband access