Millimeter Wave Integrated Access and Backhaul in 5G: Performance Analysis and Design Insights

Abstract

With the emergence of integrated access and backhaul (IAB) in the fifth generation (5G) of cellular networks, backhaul is no longer just a passive capacity constraint in cellular network design. In fact, this tight integration of access and backhaul is one of the key ways in which 5G millimeter wave (mmwave) heterogeneous cellular networks (HetNets) differ from traditional settings where the backhaul network was designed independently from the radio access network (RAN). With the goal of elucidating key design trends for this new paradigm, we develop an analytical framework for a two-tier HetNet with IAB where the macro base stations (MBSs) provide mm-wave backhaul to the small cell base stations (SBSs). For this network, we derive the downlink rate coverage probability for two types of resource allocations at the MBS: 1) integrated resource allocation (IRA): where the total bandwidth (BW) is dynamically split between access and backhaul, and 2) orthogonal resource allocation (ORA):where a static partition is defined for the access and backhaul communications. Our analysis concretely demonstrates that offloading users from the MBSs to SBSs may not provide similar rate improvements in an IAB setting as it would in a HetNet with fiber-backhauled SBS. Our analysis also shows that it is not possible to improve the user rate in an IAB setting by simply densifying the SBSs due to the bottleneck on the rate of wireless backhaul links between MBS and SBS. Index TermsIntegrated access and backhaul, heterogeneous cellular network, mm-wave, 3GPP, wireless backhaul, stochastic geometry.The authors are with Wireless@VT,

On Integrated Access and Backhaul Networks: Current Status and Potentials

“…Consequently, in all figures except for Fig. 6, we ignore the interference in the backhaul links, in harmony with, e.g., [27]- [29]. In Fig.…”

“…Also, we let the UE antenna gain to be 0 dB. This is in harmony with, e.g., [27], [29], [48], and because the UE has an omni-directional radiation pattern. For discussions on how the antenna gain is affected by the antenna array properties, see, e.g., [45].…”

“…The impact of dynamic time division duplex (TDD)based resource allocation on the throughput of IAB networks, how its performance compares with static TDD and FDD (F: frequency), is discussed in [25], [26]. Moreover, [27]- [29] characterize the coverage probability of IAB-enabled mmWave heterogeneous networks via infinite Poisson point processes (PPPs). Precoder design and power allocation, to maximize the network sum rate, is considered in [30].…”

Full-Duplex Two-Tier Heterogeneous Network With Decoupled Access: Cell Association, Coverage, and Spectral Efficiency Analysis

“…1 [24], however this would result in additional complexity in the derivation of analytical expressions without providing any new design insights. The rationale behind this is the fact that performance trends are kind of robust to the underlying fading distribution as far as the employed fading distribution has distancedependent channel components [25]. Therefore, the Rayleigh distribution's well-established mathematical tractability makes it a key ingredient in the analysis of mmWave systems as well [26].…”

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“…The main advantages of wireless backhauling over traditional wired backhauling are the implementation flexibility, cost efficiency, and lowcomplexity maintenance processes. Moreover, integrated access and backhauling is considered as a promising approach to reduce the deployment cost in ultra-dense networks [7]- [9]. Therefore, wireless backhauling has attracted extensive research attention to develop efficient backhauling solutions.…”