Reliable and Efficient Multicast Communication in WiFi Direct (P2P) 802.11Wireless Networks

Abstract

This thesis focuses on exploring a multicast communication protocol forWiFi Direct (WD) 802.11 networks. The aim is to improve reliability and efficiency of multicast communication in WD networks. Multicast inWDhas numerous potential applications such as local content sharing, sharing network services, playing multi-player games, and a number of other proximity based services in various fields, viz. health, sports, agriculture, transportation, and gaming. The two major issues with multicast, reliability and efficiency, have been extensively studied in literature for standard WiFi 802.11 networks. However, multicast protocols used in standard WiFi 802.11 networks cannot be straightforwardly used in WD networks because the two technologies are different. Some of these differences include multicast group formation, group architecture, network topology, role and capacity of multicast transmitter. As a result, a multicast protocol cannot achieve reliability and efficiency without taking into account the specifications of the MAC and PHY layers of WD 802.11 networks. Motivated from the leader based approaches of standard WiFi, an Enhanced Leader Based Multicast (ELBM) protocol is proposed to achieve reliability in multicast communication in WD networks. It reduces collision and interference in multicast data transmission by improving the channel access mechanism and selecting an optimal representative multicast receiver. In order to assess the performance improvement which results from early detection of packet collision, Early Packet Loss Detection (EPLD) analytical model is proposed, which surpasses the standard protocol in terms of system throughput. Similarly, a theoretical model is formulated to investigate the new features of the MAC and PHY layers of 802.11ac, such as different Multiple In Multiple Out (MIMO) configurations, Modulation and Coding Schemes (MCS), and wider channel bandwidths under TGn channel models. Because hidden nodes can largely affect the throughput of WD networks, therefore an improved analytical model known as Vidden is developed to analyse the Very High Throughput (VHT) of 802.11ac in the presence of hidden stations. Vidden carefully calculates the collision probability by taking into account both the contending, as well as, the hidden stations A novel adaptive algorithm is proposed to maximize the efficiency of WD 802.11 networks under a TGn channel model by choosing optimal PHY parameters in accordance with targeted Quality of Experience (QoE) for a particular application. The simulation results show that the proposed method outperforms the standard method, thereby achieving an optimal performance in an adaptive manner. Thereafter, an efficient methodology is proposed to reduce the overall Packet Error Rate (PER) based on the simulation results. Finally, the problem of selecting the most favourable transmission channel and rate is investigated for a multicast communication system in the context of WD 802.11 networks. To this end, a novel Multi-rate Multi-channel Multicast (M3-Cast) protocol is proposed, which not only chooses the most favourable communication channel and transmission rate but also takes into account the implementation details of the underlying WD technology, thereby optimizing the overall system performance. M3-Cast is formulated analytically and evaluated by a complete system level simulation. The detailed results and analysis consider a number of performance metrics, such as bit error rate (BER), multicast capacity, and system throughput under different MIMO configurations, channel bandwidths, and various network radii. Consequently, the simulation and analytical results show that M3-Cast protocol outperforms the standard multicast protocol of WD by almost two-fold in terms of system throughput.