Interference management and system optimisation for Femtocells technology in LTE and future 4G/5G networks

Femtocells are seen to be the future of Long Term Evaluation (LTE) networks to improve the performance of indoor, outdoor and cell edge User Equipments (UEs). These small cells work efficiently in areas that suffer from high penetration loss and path-loss to improve the coverage area. It is said that 30% of total served UEs in LTE networks are vehicular, which poses challenges in LTE networks due to their high mobility, high vehicular penetration loss (VPL), high path loss and high interference. Therefore, self-optimising and dynamic solutions are required to incorporate more intelligence into the current standard of LTE system. This makes the network more adaptive, able to handle peak data demands and cope with the increasing capacity for vehicular UEs. This research has drawn a performance comparison between vehicular UEs who are served by Mobile-Femto, Fixed-Femto and eNB under different VPL scales that range between highs and lows e.g. 0dB, 25dB and 40dB. Deploying Mobile-Femto under high VPLs has improved the vehicular UE Ergodic capacity by 1% and 5% under 25dB and 40dB VPL respectively as compared to other eNB technologies. A noticeable improvement is also seen in signal strength, throughput and spectral efficiency. Furthermore, this research discusses the co-channel interference between the eNB and the Mobile-Femto as both share the same resources and bandwidth. This has created an interference issue from the downlink signals of each other to their UEs. There were no previous solutions that worked efficiently in cases where UEs and base stations are mobile. Therefore, this research has adapted an efficient frequency reuse scheme that worked dynamically over distance and achieved improved results in the signal strength and throughput of Macro and Mobile-Femto UE as compared to previous interference management schemes e.g. Fractional Frequency Reuse factor1 (NoFFR-3) and Fractional Frequency Reuse factor3 (FFR-3). Also, the achieved results show that implementing the proposed handover scheme together with the Mobile-Femto deployment has reduced the dropped calls probability by 7% and the blocked calls probability by 14% compared to the direct transmission from the eNB. Furthermore, the outage signal probabilities under different VPLs have been reduced by 1.8% and 2% when the VPLs are 25dB and 40dB respectively compared to other eNB technologies

Advanced Relaying Concepts for Future Wireless Networks

Relaying is undoubtedly a key technology for future wireless networks as it can be applied to provide coverage extension and capacity increase in a cost-effective manner. This paper presents an outline of the major advanced relaying concepts that will be part of future systems from the viewpoint of the ARTIST4G European project. These concepts can be divided into three categories, those pertinent to type-1 relays, type-2 relays and moving relays. The characteristics of each of these concepts are presented and the challenges related to their implementation are discussed. Furthermore the paper proposes a set of solutions to address the discussed challenges. For type-1 relays, the paper presents solutions for the allocation of resources to the backhaul and the access links, the inter-relay interference mitigation, and the multi-hop transmission mode. For type-2 relays, our focus is on the design of distributed hybrid automatic repeat request (HARQ) protocols. More specifically we propose that the conventional HARQ schemes are adapted to exploit the potentially better channel conditions provided by the relays. Moreover distributed turbo coding solutions are introduced for increasing transmission reliability with the aid of relays. Finally, moving relays are presented as an efficient solution to the ever-growing demand for wireless broadband by users within public transportation vehicles. We show that moving relays can very effectively overcome vehicle penetration losses and boost the achievable capacities of the moving users. Overall, we conclude that the presented advanced relaying concepts are very promising and can significantly enhance the user experience in future wireless networks

Advanced Relaying Concepts for Future Wireless Networks

Relaying is undoubtedly a key technology for future wireless networks as it can be applied to provide coverage extension and capacity increase in a cost-effective manner. This paper presents an outline of the major advanced relaying concepts that will be part of future systems from the viewpoint of the ARTIST4G European project. These concepts can be divided into three categories, those pertinent to type-1 relays, type-2 relays and moving relays. The characteristics of each of these concepts are presented and the challenges related to their implementation are discussed. Furthermore the paper proposes a set of solutions to address the discussed challenges. For type-1 relays, the paper presents solutions for the allocation of resources to the backhaul and the access links, the inter-relay interference mitigation, and the multi-hop transmission mode. For type-2 relays, our focus is on the design of distributed hybrid automatic repeat request (HARQ) protocols. More specifically we propose that the conventional HARQ schemes are adapted to exploit the potentially better channel conditions provided by the relays. Moreover distributed turbo coding solutions are introduced for increasing transmission reliability with the aid of relays. Finally, moving relays are presented as an efficient solution to the ever-growing demand for wireless broadband by users within public transportation vehicles. We show that moving relays can very effectively overcome vehicle penetration losses and boost the achievable capacities of the moving users. Overall, we conclude that the presented advanced relaying concepts are very promising and can significantly enhance the user experience in future wireless networks