Design aspects of network assisted device-to-device communications


Device-to-device (D2D) communications in cellular spectrum supported by a cellular infrastructure holds the promise of three types of gains. The proximity of user equipments (UE) may allow for extremely high bit rates, low delays and low power consumption [1]. The reuse gain implies that radio resources may be simultaneously used by cellular as well as D2D links, tightening the reuse factor even of a reuse-1 system [2]. Finally, the hop gain refers to using a single link in the D2D mode rather than using both an uplink and a downlink resource when communicating via the access point in the cellular mode. Additionally, D2D communications may extend the cellular coverage and facilitate new types of wireless peer-to-peer services [2, 3]. However, D2D communications utilizing cellular spectrum poses new challenges, because relative to cellular communication scenarios, the system needs to cope with new interference situations. For example, in an orthogonal frequency division multiplexing (OFDM) system in which D2D communication links may reuse some of the OFDM time-frequency resources (physical resource blocks, PRB), intracell interference is no longer negligible [4]. In addition, in multicell systems, new types of intercell interference situations have to be dealt with due to the undesired proximity of D2D and cellular transmitters and receivers. Interestingly, these new types of interference situations are intertwined with the duplexing scheme that the cellular network and the D2D link employ, and also depend on the spectrum bands and PRBs allocated to D2D links. For example, when a D2D link utilizes some of the cellular uplink PRBs, a transmitting cellular user equipment (UE) may cause much stronger interference to a receiving UE of a D2D pair in a neighbor cell than the interference caused to a radio base station in that same neighbor cell. Solution approaches to deal with this problem include power control [5], various interference avoiding multi-antenna transmission techniques [6] that can be combined with proper mode selection — which decides whether a D2D candidate pair should be communicating in D2D or in cellular mode [7] — and advanced (network) coding schemes [1]. The purpose of the current article is to provide a brief overview of the main technical challenges that need to be addressed to realize the potential gains of D2D communications and propose solution approaches to these challenges. Throughout we will assume OFDM as the transmission scheme and the 3GPP Long Term Evolution (LTE) system as our baseline for D2D design [10]. The key functions of D2D communications include peer discovery, physical layer procedures, such as synchronization and reference signal design, and various radio resource management functions including mode selection, scheduling, PRB allocation, power control, and intraand intercell interference management. We structure the article as follows. The next section presents D2D scenarios and discusses the role of a cellular infrastructure in peer discovery and radio resource management. We briefly overview the key design challenges for D2D communications. Next, we focus on peer discovery and examine the role of the network in this important procedure. We discuss radio resource management issues, including mode selection, scheduling, channel quality estimation, and power control in the mixed D2D and cellular environment. We discuss simulation results ABSTRACT

DOI: 10.1109/MCOM.2012.6163598

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@article{Fodor2012DesignAO, title={Design aspects of network assisted device-to-device communications}, author={G{\'a}bor Fodor and Erik Dahlman and Gunnar Mildh and Stefan Parkvall and Norbert Reider and Gy{\"{o}rgy Mikl{\'o}s and Zolt{\'a}n Richard Tur{\'a}nyi}, journal={IEEE Communications Magazine}, year={2012}, volume={50}, pages={170-177} }