5G mobile networks are expected to provide pervasive high speed wireless connectivity, to support increasingly resource intensive user applications. Network hyper-densification therefore becomes necessary, though connecting to the Internet tens of thousands of base stations is non-trivial, especially in urban scenarios where optical fibre is difficult and costly to deploy. The millimetre wave (mm-wave) spectrum is a promising candidate for inexpensive multi-Gbps wireless backhauling, but exploiting this band for effective multi-hop data communications is challenging. In particular, resource allocation and scheduling of very narrow transmission reception beams requires to overcome terminal deafness and link blockage problems, while managing fairness issues that arise when flows encounter dissimilar competition and traverse different numbers of links with heterogeneous quality. In this paper, we propose WiHaul, an airtime allocation and scheduling mechanism that overcomes these challenges specific to multi-hop mm-wave networks, guarantees max-min fairness among traffic flows, and ensures the overall available backhaul resources are fully utilised. We evaluate the proposed WiHaul scheme over a broad range of practical network conditions, and demonstrate up to 5 times individual throughput gains and a fivefold improvement in terms of measurable fairness, over recent mm-wave scheduling solutions.
Hemanth and Venkatesh analyse the performance of the 802.11ad SP mechanism in terms of frame delay @cite_52 . Several works build upon the 802.11ad standard and specify MAC protocol improvements for single-hop WLANs @cite_37 @cite_46 @cite_14 . Chandra employ adaptive beamwidth to achieve improved channel utilisation @cite_37 . Sim exploit dual-band channel access to address terminal deafness and improve throughput @cite_46 . Optimal client association and airtime allocation is pursued in @cite_41 to maximise the utility of enterprise mm-wave deployments.
@cite_37 @cite_14 @cite_41 @cite_52 @cite_46
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In this paper, we consider the directional multigigabit (DMG) transmission problem in IEEE 802.11ad wireless local area networks (WLANs) and design a random-access-based medium access control (MAC) layer protocol incorporated with a directional antenna and cooperative communication techniques. A directional cooperative MAC protocol, namely, D-CoopMAC, is proposed to coordinate the uplink channel access among DMG stations (STAs) that operate in an IEEE 802.11ad WLAN. Using a 3-D Markov chain model with consideration of the directional hidden terminal problem, we develop a framework to analyze the performance of the D-CoopMAC protocol and derive a closed-form expression of saturated system throughput. Performance evaluations validate the accuracy of the theoretical analysis and show that the performance of D-CoopMAC varies with the number of DMG STAs or beam sectors. In addition, the D-CoopMAC protocol can significantly improve system performance, as compared with the traditional IEEE 802.11ad MAC protocol. Abstract 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. We present an analytical model for the access during the Service Periods (SP) of the IEEE 802.11ad Hybrid Medium Access Control protocol. As a performance measure of this protocol, we derive the worst case and average delay faced by the SP packets. We show that as the arrival rate of the SP packets increases, the delay increases linearly till a point, beyond which it grows exponentially. Further, we extend the model to variable length of beacon interval, and random allocation of SPs to the nodes. We show how a network designer can do optimal allocation of the SP and the CBAP duration to achieve a tradeoff between SP delay and CBAP throughput. We further extend our analysis for the case of heterogeneous system. Our analytical results are compared with simulation and the results show a good match. Achieving multi-gigabit per second data rates, millimeter wave communication promises to accommodate future and current demands for very high speed wireless data transmission. However, the mandatory use of directional antennas brings significant challenges for the design of efficient MAC layer mechanisms. In particular, IEEE 802.11ad for the 60 GHz band lacks omni-directional transmissions and carrier sensing. This prevents stations from overhearing the actions of other stations, the so called “deafness” problem, which substantially impairs the efficiency and fairness of CSMA CA medium access. Most existing solutions to this problem depend on properties of lower frequency bands and thus do not apply to 60 GHz. In this paper, we propose a dual-band MAC protocol combining 60 GHz communication with co-existing 5 GHz interfaces. By broadcasting control messages on 5 GHz frequencies, we solve the deafness problem and can use the 60 GHz band exclusively for high rate data transmission. While our approach occupies air time on the 5 GHz band for control messages, it does achieve a net throughput gain (over both bands) of up to 65.3 compared to IEEE 802.11ad. In addition, our simulation results show an improvement of MAC fairness of up to 42.8 over IEEE 802.11ad.