Cross-Tier Dual-Connectivity Designs of Three-Tier Hetnets With Decoupled Uplink/Downlink and Global Coverage Performance Evaluation

Abstract

In the conventionally coupled uplink (UL) and downlink (DL) association (CUDA) scheme, the UL performance is limited greatly by the DL parameters such as the density and power of base stations (BSs). To overcome this issue, this paper focuses on a novel three-tier heterogeneous network (HetNet) as well as global performance evaluation, where the cross-tier dual-connectivity (DC) and decoupled UL and DL association (DUDA) are integrated. On one hand, with the cross-tier DC, in DL or UL, typical user equipment is associated simultaneously with the primary and secondary BSs that are located at different tiers. On the other hand, with DUDA the primary and secondary access points of UL and DL are not necessarily the same. The proposed cross-tier DC scheme meets the need of the next generation networks where control channel comes from Macro BS and data channels from small cell BSs. For such HetNets, the work first presents a comprehensive investigation of the cross-tier DC design of all possible DUDA modes and the corresponding association conditions. Second, by simplifying the association conditions the work gives the comprehensive derivations in terms of the association probabilities and the statistical descriptions of the primary and secondary UL access distances. Third, by using the method from stochastic geometry this paper derives the general form of UL coverage probabilities by creating a common model of DUDA designs so that the global UL average coverage probability (ACP) of the whole network is achieved. The presented numerical and simulated analysis first validates the derivations. Then, the analysis focuses on the global UL ACP comparison of the whole HetNet between the DUDA and CUDA designs. The comparison of global ACP shows that the ACP of DUDA design is higher than the one of the CUDA design. Although the powers and densities of BSs impose the outstanding impact on the ACP of the CUDA designs, they have a very limited effect on one of the DUDA designs due to the utilization of decoupling association. INDEX TERMS Heterogeneous networks, decoupling association, dual-connectivity, cross-tier access.

Resource allocation in 5G heterogeneous networks with downlink‐uplink decoupled access

“…• DUDe access scheme is investigated by researchers [15][16][17][18][19][20][21][22][23][24] considering two-tier HetNet. Researchers [25][26][27][28] investigated DUDe access scheme in three-tier HetNet.…”

“…However, to the best of the authors' knowledge, the following gaps in past work remained untouched by researchers. DUDe access scheme is investigated by researchers considering two‐tier HetNet. Researchers investigated DUDe access scheme in three‐tier HetNet. Using optimization theory, performance analysis of DUCo access vs DUDe access scheme in four‐tier HetNet is still an open area for research. In the past research works, mobile data traffic imbalances in terms of user associated/attached in DL and UL are not pointed out in four‐tier DUCo HetNet. Subsequently, mobile data traffic offloading and loading among macro BS, small BS, Wi‐Fi, and D2D in terms of user associated/attached in DL and UL is still open for research in four‐tier DUDe HetNet. …”

“…Moreover, expressions of probability of association, probability of coverage, percentage in decoupled, and area throughput are derived employing stochastic geometry in decoupled DL and uplink, respectively. Jia et al investigated dual connectivity for all possible DL and UL Decoupled access modes, derived association probabilities after simplifying the conditions for association, and derived UL coverage probabilities using tools from stochastic geometry to achieve UL average coverage probability. Exploring cell association and objective of throughput maximization in DUDe HetNet environment, Razlighi et al proposed optimal distributed dynamic time‐division‐duplex schemes in half duplex system to select DL or UL transmission based on quality of channel in a given time slot in DUDe HetNet scenarios.…”

Partial Interference Alignment Scheme for Three-Tier Downlink Heterogeneous Networks

“…In this paper, we focus on the three-tier downlink partially connected relay HetNet, which is composed of one MBS, two PBSs and an amplify-and-forward (AF) relay with halfduplex mode, and propose the partial IA scheme. Different from the "three-tier HetNet" in [29] which consists of macro, pico and femto tiers, the term "three-tier HetNet" in this paper refers to MBS, PBSs and relay. Since the proposed scheme can handle the co-tier, cross-tier and cross time slot interference at the same time, we simply refer to it as the CCSIA scheme.…”

Dual Connectivity in Decoupled Aerial HetNets With Reverse Frequency Allocation and Clustered Jamming

“…To further improve the performance of cellular networks, the dual connectivity (DC) paradigm has been proposed to enhance reliable connectivity, capacity, and coverage of the aerial HetNets [12]- [14]. In DC, the UEs are allowed to maintain more than one connection with the UAVs in uplink (UL) and downlink (DL).…”