Syed Fahad Yunas

Spectral and energy efficiency of ultra-dense networks under different deployment strategies

To tackle the 1000× mobile data challenge, the research towards the 5th generation of mobile cellular networks is currently ongoing. One clear enabler toward substantially improved network area capacities is the increasing level of network densification at different layers of the overall heterogeneous radio access system. Ultra-dense deployments, or DenseNets, seek to take network densification to a whole new level, where extreme spatial reuse is deployed. This article looks into DenseNets from the perspectives of different deployment strategies, covering the densification of the classical macro layer, extremely dense indoor femto layer, as well as outdoor distributed antenna system (DAS), which can be dynamically configured as a single microcell or multiple independent microcells. Also, the potential of a new indoor-to-outdoor service provisioning paradigm is examined. The different deployment solutions are analyzed from the network area spectral and network energy efficiency perspectives, with extreme densification levels, including both indoor and outdoor use scenarios. The obtained results indicate that dedicated indoor solutions with densely deployed femtocells are much more spectrum- and energy-efficient approaches to address the enormous indoor capacity demands compared to densifying the outdoor macro layer, when the systems are pushed to their capacity limits. Furthermore, the dynamic outdoor DAS concept offers an efficient and capacity-adaptive solution to provide outdoor capacity, on demand, in urban areas.

Techno-economical analysis and comparison of legacy and ultra-dense small cell networks

Network densification has been identified as one key enabling technology to address the 1000x mobile data challenge. This article analyzes network densification from the different deployment options perspective by looking into three mainstream technologies; Macrocells, Microcells, and Femtocells. The technologies are evaluated in a suburban neighborhood with modern residential houses. As majority of the data traffic in the network is believed to be generated by indoor users, we make a techno-economic analysis and comparison of the different deployment strategies from the indoor local area service provisioning viewpoint. Results show superior performance of low power indoor femtocell based deployment solutions in terms of coverage, capacity, energy and cost efficiency as compared to the outdoor solutions. Densifying the traditional pure Macro or Micro layers does provide improvement in the indoor coverage levels, however, due to the closer proximity of the co-channel interfering sites, the achievable capacity in the indoor environment deteriorates, which in turn also affects the energy and cost efficiency. These findings strongly motivate towards ultra dense deployments, based on indoor femtocell solutions, for addressing the local area capacity needs of the emerging future 5G networks.

Deployment strategies and performance analysis of Macrocell and Femtocell networks in suburban environment with modern buildings

In this article, we study and analyze the impact of modern buildings, with increased building penetration losses (BPLs), on different cellular deployment strategies based on traditional outdoor (macro) and dedicated indoor (femto) solutions in a suburban environment. The analysis covers both indoor and outdoor use cases, and the performance of the deployment strategies is evaluated in terms of network coverage, spectral and energy efficiency. The obtained results indicate that the indoor performance of pure macrocellular network in terms of coverage, capacity and energy efficiency is highly degraded with increasing wall penetration losses of modern buildings. Hence, the best strategy to overcome this problem is by deploying indoor femtocells, whose indoor performance is shown to actually benefit from increased BPLs. However, the outdoor performance of pure femtocell deployment is shown to degrade due to increased BPLs. Stemming from this, a heterogeneous Macro-Femto co-channel deployment solution is also analyzed and shown to deliver a balanced performance for both outdoor and indoor environments in terms of coverage, capacity and energy efficiency. These findings strongly motivate towards heterogeneous network deployments in the future, where indoor network elements play an increasingly important role.

Impact of network densification, site placement and antenna downtilt on the capacity performance in microcellular networks

In this paper we evaluate the capacity performance of a microcellular network deployment in a dense urban Manhattan grid environment. Different microcellular layouts with varying cell densities per sq. km are investigated, while considering the outdoor and as well as indoor propagation environments. Three main capacity enhancing techniques, network densification, site placement and antenna downtilt are utilized and their effect on cell spectral efficiency and area spectral efficiency is assessed. As a result of densification, the network capacity for outdoor environment can be improved since the area spectral efficiency increases. However, due to significant reduction of cell spectral efficiency, the area spectral efficiency starts to saturate for indoor environments. The results also indicate that careful site placement can enhance the capacity performance in both outdoor and indoor environments. Moreover, antenna downtilt configuration is shown to improve the area capacity in the outdoor environment with minor improvement for indoor environments. The results hence indicate that microcellular network densification suffers from capacity inefficiency even when performance techniques like antenna downtilt is utilized. This calls for alternative methods to deploy networks, e.g., indoor networks.

Performance of Spotlight coverage in managing the Interference in multi-antenna cellular environment

This paper presents a unique concept of ‘Spotlight coverage’ for outdoor multi-antenna (or DAS) cellular systems. This concept helps in achieving high Signal-to-Interference Ratio (SIR) throughout the cell coverage area by effectively controlling the leakage into the neighboring cells. Interference and coverage analysis of traditional wall mounted and street lamp mounted (providing spotlight coverage) multi-antenna cell have been presented and compared. Results show considerable improvement in the SIR for street lamp mounted multi-antenna cells.

Techno-Economical Comparison of Dynamic DAS and Legacy Macrocellular Densification

AbstractIn order to support anywhere and anytime services of Beyond 4G networks, new deployment solutions will be required that can cost-effectively address the capacity demand of the future and also offer consistently high bit rates and decent quality of service throughout the network coverage area. In this article we look into an advanced outdoor distributed antenna system (DAS) concept, dynamic DAS, that offers on-demand outdoor capacity in urban areas by dynamically configuring the remote antenna units to either act as individual small cells or distributed nodes of a common central cell. The performance of the investigated DAS solution is evaluated and compared with legacy macrocellular deployment in a dense urban environment. Furthermore, the analysis covers the performance evaluation, mainly from an outdoor perspective. The obtained results indicate superior performance of dynamic DAS concept in terms of coverage and SINR, network capacity and cost-efficiency as compared to legacy macrocellular network deployments.

Spectral efficiency of dynamic DAS with extreme down-tilt antenna configuration

The current outdoor deployments, dominated by macrocellular layer, inherently lacks the capabilities for supporting the anywhere and anytime services of Beyond 4G (B4G) networks. Hence, new deployment solutions are required that can cost-effectively address the capacity demand of the future and also offer consistently high bit rates and decent quality of service (QoS) throughout the network coverage area. This article looks into an advanced outdoor distributed antenna system (DAS) concept as a potential solution for fulfilling the requirements of 5G era. The investigated DAS solution can dynamically configure itself as a single super microcell or multiple independent small microcells, based on the outdoor traffic conditions. We evaluate the performance of dynamic DAS using two antenna configurations based on; (i) No-tilt (utilizing Omni-directional antenna) and (ii) Extreme tilt (utilizing wide beam directional antenna). Furthermore, the analysis covers the performance evaluation, mainly from an outdoor perspective while taking into account two key performance metrics: coverage and spectral efficiency. The obtained results indicate that the dynamic outdoor DAS concept can offer an efficient and capacity-adaptive solution to provide on-demand outdoor capacity in urban areas. Moreover, the extreme tilt configuration is shown to improve the cell and area spectral efficiency of dynamic DAS, in outdoor dense urban environment, by effectively controlling the inter-cell interference.

Multi-antenna cell constellations for interference management in dense urban areas

The aim of this paper is to present and propose different multi-antenna cell constellations based on outdoor distributed antenna system implementation. The idea of the outdoor DAS is to reduce interference in dense urban areas in order to achieve very high signal-to-interference-ratios (SIR) which defines the data throughput available to the user. Moreover, the SIR distribution over the network coverage area has to be as constant as possible in order to keep throughput in maximum and constant. Analysis of different multi-antenna constellations are presented and interference behavior is compared to independent small cell i.e. micro/pico/femto cells. The obtained results show superior SIR distribution for multi-antenna layout compared to independent small cells. Strategic antenna placement and configuration of eight antennas per cell result in average SIR of 23 dB over the cell coverage area.

Technoeconomical Analysis of Macrocell and Femtocell Based HetNet under Different Deployment Constraints

Ultradense deployment of small cells is being considered as one of the key flavors of the emerging 5G cellular networks to address the future data capacity challenges. A large share of these deployments will be indoor, as this is the arena where the majority of the data traffic is believed to originate from in the future. Indoor small cell solutions (e.g., femtocell or WiFi) are well positioned for delivering superior indoor coverage and capacity. However, due to relatively smaller coverage footprint compared to traditional macrocells, a very dense deployment of small cells will be needed in order to have a ubiquitous indoor coverage. Such dense deployment triggers cost and energy efficiency concerns for mobile operators. In this paper, we analyze and compare the technoeconomic performance of two deployment strategies: homogeneous macrocellular densification and heterogeneous macro-femto deployment strategy, from an indoor service provisioning perspective. Particularly, we analyze and contrast the performance of macro-femto based deployment, with varying femtocell market penetration rate and under different femtocell backhaul connectivity constraints, with that of homogeneous macrocellular densification. The results indicate superior performance of indoor femtocell based deployment as compared to macrocellular-only densification, due to better indoor coverage, radio channel conditions, and high degree of spatial reuse.