Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Toward Distributed User Scheduling and Coordinated Beamforming in Multi-Cell mmWave Networks: A Sensing-Assisted Framework

Tenghao Cai, Lei Li, Shutao Zhang, Tsung-Hui Chang

Abstract

Providing guaranteed quality of service for cell-edge users remains a longstanding challenge in wireless networks. While coordinated interference management was proposed decades ago, its potential has been limited by computational complexity and backhaul resource constraints. Distributed user scheduling and coordinated beamforming (D-USCB) offers a scalable solution but faces practical challenges in acquiring inter-cell channel state information (CSI), as base stations (BSs) are often restricted to signal strength measurements, and high-dimensional CSI exchange incurs substantial overhead. Inspired by integrated sensing and communication (ISAC), this paper proposes a sensing-assisted D-USCB (SD-USCB) framework to maximize the network throughput of multi-cell mmWave networks. Firstly, the framework leverages channel knowledge maps (CKMs) that map user locations to CSI estimates, where user locations are proactively sensed via ISAC echoes. Secondly, we employ a signal-to-average-leakage-plus-interference-plus-noise ratio (SALINR) metric for distributed ISAC beamforming optimization, in which BSs simultaneously communicate with users and sense their locations. These two components jointly enable distributed coordinated transmission with only user location information exchanged among BSs, thereby substantially reducing backhaul overhead. In addition, we devise efficient distributed user scheduling and ISAC beamforming algorithms to jointly optimize communication and sensing performance. Extensive numerical results demonstrate significant improvements in network throughput, validating the efficacy of the proposed framework.

Toward Distributed User Scheduling and Coordinated Beamforming in Multi-Cell mmWave Networks: A Sensing-Assisted Framework

Abstract

Providing guaranteed quality of service for cell-edge users remains a longstanding challenge in wireless networks. While coordinated interference management was proposed decades ago, its potential has been limited by computational complexity and backhaul resource constraints. Distributed user scheduling and coordinated beamforming (D-USCB) offers a scalable solution but faces practical challenges in acquiring inter-cell channel state information (CSI), as base stations (BSs) are often restricted to signal strength measurements, and high-dimensional CSI exchange incurs substantial overhead. Inspired by integrated sensing and communication (ISAC), this paper proposes a sensing-assisted D-USCB (SD-USCB) framework to maximize the network throughput of multi-cell mmWave networks. Firstly, the framework leverages channel knowledge maps (CKMs) that map user locations to CSI estimates, where user locations are proactively sensed via ISAC echoes. Secondly, we employ a signal-to-average-leakage-plus-interference-plus-noise ratio (SALINR) metric for distributed ISAC beamforming optimization, in which BSs simultaneously communicate with users and sense their locations. These two components jointly enable distributed coordinated transmission with only user location information exchanged among BSs, thereby substantially reducing backhaul overhead. In addition, we devise efficient distributed user scheduling and ISAC beamforming algorithms to jointly optimize communication and sensing performance. Extensive numerical results demonstrate significant improvements in network throughput, validating the efficacy of the proposed framework.

Paper Structure

This paper contains 23 sections, 1 theorem, 48 equations, 11 figures, 1 table, 2 algorithms.

Table of Contents

  1. Introduction
  2. Related Works
  3. Multi-cell Coordinated Transmission
  4. ISAC and sensing-assisted communication
  5. CKM
  6. Contributions
  7. System Model and Problem Description
  8. System Model
  9. Problem Description
  10. Proposed SD-USCB Framework
  11. CSI acquisition by CKM and proactive sensing
  12. SALINR to alleviate variable coupling and reduce the information exchange across BSs
  13. Proposed SD-USCB procedure
  14. Scheduling and BF Algorithm Design
  15. CKM construction by LSCM
  16. ...and 8 more sections

Key Result

Theorem 1

For any given set of beamformers $\{{\bm v}_n^{k_\ell}\}_{k_\ell \in \mathcal{S}_\ell}$ with $\|{\bm v}_n^{k_\ell}\| = P, \forall k_\ell \in \mathcal{S}_\ell, \ell \in {\mathcal{L}}$, under independent Rayleigh fading channels $\{{\bm h}_n^{k_\ell}\}$, it holds that where $\bar{Z}_n^{k_\ell} >0$ is a parameter dependent on the Lipchitz constant of $R_n^{k_\ell}({\mathcal{I}}_n^{k_\ell})$, $M_\el

Figures (11)

  • Figure 1: Proposed SD-USCB framework: BSs in the network transmit ISAC signals to simultaneously convey the data to users and sense the user locations. The sensed locations are then exchanged through the backhaul to enable neighboring BSs to know the locations of active users. With the exchanged locations, BSs query the pre-built CKMs to obtain the inter-cell CSI estimates for subsequent D-MCRA designs.
  • Figure 2: A cellular mmWave network, where BSs are inter-connected via limited-bandwidth backhauls. The kinematic states of user $k_\ell \in {\mathcal{U}}_\ell$ include its distance $d_{n-1}^{\ell, k_\ell}$, angle $\psi_{n-1}^{\ell, k_\ell}$ and velocity $v_{n-1}^{\ell, k_\ell}$ to its associated BS $\ell$.
  • Figure 3: The operations of BS $\ell$ in the proposed SD-USCB framework.
  • Figure 4: Illustration of the CKM construction at the left BS, whose coverage area is divided into grids. The shadowed circle represents the area where users are typically associated with the BS centered at the area. In the CKM utilization, the left BS queries its CKM with the user locations exchanged from the neighboring (right) BS to obtain the inter-cell CSI estimates.
  • Figure 5: PFR achieved by different BF algorithms versus FP iteration.
  • ...and 6 more figures

Theorems & Definitions (3)

  • Theorem 1
  • Proof 1
  • Remark 1