A novel and realistic hybrid downlink-uplink coupled/decoupled access scheme for 5G HetNets

Abstract

Abstract:Cell association in present day heterogeneous networks (HetNets) is still based on the technique used by homogeneous cellular networks despite power and coverage area disparities of network nodes. In ongoing policy, both uplink (UL) and downlink (DL) associations are coupled based on DL characteristics, which introduces UL-DL asymmetry and cell load imbalances. Recently, decoupled cell association, also known as downlink-uplink decoupling (DUDe), has been introduced in 3rd Generation Partnership Project (3GPP) Release 12 to improve uplink performance, load balancing, and cell capacity. In DUDe, characteristics of both DL and UL channels can be considered. By using this concept, various theoretical UL or DL analytical decoupled access models have been proposed without giving their practical realization.In these frameworks, all network users are assumed to use DL-UL decoupled access without considering its practical utility. Existing solutions also ignore noise, which may lead to practical inaccuracies. This paper proposes a novel and realistic hybrid scheme in which coupled or decoupled cell associations can be selected depending upon user location and its advantages. Building upon this innovative approach, it has been established that decoupled access is chosen by few users and accordingly a two-tier analysis framework for these devices has been formulated. Simple closed-form solutions for user performance metrics without ignoring noise have been precisely derived, which relate user performance with HetNet densities. Devised distributions are employed to compare the performance of the decoupled case with the ongoing procedure of coupled access. A practical network design has been proposed, which requires minimum changes to the existing network. Results show that decoupling is viable in the 5G HetNet to achieve fairness, cell load balancing, and performance improvements.

Decoupled Downlink and Uplink Access for Aerial Terrestrial Heterogeneous Cellular Networks

“…Conventionally in T-HCNs, it is assumed that for each UE, BS association is based on a DL-reference received power, where both DL and UL are provisioned through the same associated BS [27]. However, to offload the excessively loaded high-power BSs and to minimize the cumulative interference, various research works propose DL and UL decoupled (DUDe) access, where each UE is allowed to associate itself to different tier BSs in DL and UL, for improving the system's performance [27]- [29]. Traditionally, DUDe access assumes the same pathloss exponent across all the tiers to investigate the performance of multi-tier T-HCNs [27]- [30].…”

An adaptive scheduling scheme for inhomogeneously distributed wireless ad hoc networks

“…Any wireless network requires an efficient channel access scheme to ensure the coexistence of different communication links in close spatial proximity [21,22]. Under similar circumstances, different scheduling strategies are bound to perform variously with respect to different performance indicators, such as transmission capacity, the probability of outage, transmission delays, QoS, or energy consumption.…”

Performance analysis of downlink and uplink decoupled access in clustered heterogeneous cellular networks

“…It was shown that the DUDe scheme has a higher spectral-and energy-efficiency than that of the Non-DUDe scheme. Some implementation issues of DUDe are discussed in [7,11]. In the 3-GPP cellular standards, the X2 interface is responsible for the coordination and handover procedures.…”

“…The performance of the X2 interface is limited by the fact that not only the data traffic but also the control signals of the coupled as well as the non-coupled UEs are transmitted through it. To avoid traffic over-load in a busy network, the core network can also be used to route the data traffic and the control signals [7] To help limit the back-haul load and traffic latency issues over the core network, [11] proposed changes on the network side for the case of DUDe access, whereby the core network routes the UL traffic for the decoupled users only. The access scheme for non-decoupled users is suggested to route the UL and DL traffic through the same BS as in the existing 3-GPP architecture.…”

“…In [12,13] the authors derived expressions of the coverage probability and the average throughput for HCNs in which BS locations were modeled by an HPPP. On the other hand, [9,11,14] derived the expressions of coverage probability and average throughput for HCNs in which the UE locations were modeled by a HPPP. However, the HPPP modeling approach cannot accurately describe the UL interference when UEs occur in clusters, which is a probable scenario in urban hotspots such as shopping malls and sports stadiums [15].…”