Spectrum Sharing for Device-to-Device Communication in Cellular Networks (1305.4219v5)

Abstract: This paper addresses two fundamental and interrelated issues in device-to-device (D2D) enhanced cellular networks. The first issue is how D2D users should access spectrum, and we consider two choices: overlay (orthogonal spectrum between D2D and cellular UEs) and underlay (non-orthogonal). The second issue is how D2D users should choose between communicating directly or via the base station, a choice that depends on distance between the potential D2D transmitter and receiver. We propose a tractable hybrid network model where the positions of mobiles are modeled by random spatial Poisson point process, with which we present a general analytical approach that allows a unified performance evaluation for these questions. Then, we derive analytical rate expressions and apply them to optimize the two D2D spectrum sharing scenarios under a weighted proportional fair utility function. We find that as the proportion of potential D2D mobiles increases, the optimal spectrum partition in the overlay is almost invariant (when D2D mode selection threshold is large) while the optimal spectrum access factor in the underlay decreases. Further, from a coverage perspective, we reveal a tradeoff between the spectrum access factor and the D2D mode selection threshold in the underlay: as more D2D links are allowed (due to a more relaxed mode selection threshold), the network should actually make less spectrum available to them to limit their interference.

• The paper derives analytical expressions for both overlay and underlay spectrum sharing, revealing key tradeoffs in interference and resource allocation.
• It employs a stochastic geometric framework with a spatial Poisson point process to accurately model user positions and interference effects.
• Results demonstrate that optimal mode selection and spectrum partitioning can balance performance and interference in integrating D2D with cellular networks.

Spectrum Sharing for Device-to-Device Communication in Cellular Networks

The paper "Spectrum Sharing for Device-to-Device Communication in Cellular Networks" by Xingqin Lin, Jeffrey G. Andrews, and Amitabha Ghosh investigates two critical issues in the integration of Device-to-Device (D2D) communications within cellular networks: spectrum access methods and mode selection for D2D communications. The text uses a stochastic geometric framework to provide an analytical perspective on the potential configuration of D2D communications, evaluating both overlay and underlay spectrum sharing strategies.

Overview

The research focuses on understanding how D2D users can access the cellular spectrum, either through orthogonal allocation (overlay) or shared allocation (underlay), and determining the optimal mode selection between direct communication and communication via the base station. This decision inherently depends on the distance between the D2D transmitter and receiver. A hybrid network model, gauging mobile positions via a spatial Poisson point process, underpins the evaluation, allowing for an encompassing performance assessment.

Prominent in this paper is the classification of D2D spectrum sharing into in-band and out-of-band modalities. The former can be further divided into overlay and underlay scenarios, depending on whether D2D and cellular transmissions use orthogonal resources or share the same spectral allocation.

Analytical Framework and Findings

The authors derive analytical expressions for data rates applicable to both spectrum access strategies. Employing a Poisson point process to model interference leads to insightful observations:

1. Overlay D2D: The rate analysis reveals that as the D2D communication threshold increases, spectrum partitioning remains stable, provided the threshold is suitably large. This implies the overlay scenario can maintain robust performance regardless of D2D user density increases.
2. Underlay D2D: Conversely, as the potential for D2D links grows under this shared access scenario, the spectrum allocated to these links must decrease to manage interference levels effectively.

The findings underline a tradeoff intrinsic to the underlay scenario—a balance between spectrum access and D2D mode selection thresholds ensures optimal performance while limiting interference among concurrent links.

Implications and Future Directions

The implications for cellular network design are substantial. By demonstrating that both spectrum sharing strategies can robustly support D2D communications without severely impacting cellular transmissions, the paper provides a basis for further exploration into hybrid network architectures that can effectively weave D2D functionality into existing infrastructure.

The work opens several avenues for future research. Extending these findings to heterogeneous networks with multiple node types presents one intriguing possibility. Moreover, exploring the integration of multi-antenna techniques and enhancing D2D communications through robust scheduling mechanisms and cooperative strategies could yield richer models and insights.

Overall, this research establishes important baseline models and frameworks for optimizing spectrum sharing in cellular networks with burgeoning D2D communication capabilities. It offers a comprehensive analysis vital for both theoretical exploration and practical application in the evolving landscape of modern telecommunications.