Energy Efficiency and Spectral Efficiency Tradeoff in Device-to-Device (D2D) Communications

Abstract

In this letter, we investigate the tradeoff between energy efficiency (EE) and spectral efficiency (SE) in device-todevice (D2D) communications underlaying cellular networks with uplink channel reuse. The resource allocation problem is modeled as a noncooperative game, in which each user equipment (UE) is self-interested and wants to maximize its own EE. Given the SE requirement and maximum transmission power constraints, a distributed energy-efficient resource allocation algorithm is proposed by exploiting the properties of the nonlinear fractional programming. The relationships between the EE and SE tradeoff of the proposed algorithm and system parameters are analyzed and verified through computer simulations. Index Terms-EE and SE tradeoff, D2D communication, noncooperative game, nonlinear fractional programming.

Energy Efficiency in MIMO Underlay and Overlay Device-to-Device Communications and Cognitive Radio Systems

“…Fractional programming is employed assuming no multi-user interference is present. The trade-off between energy efficiency and spectral efficiency in D2D communications has been analyzed in [29].…”

“…Instead, (29b) depends on both optimization variables and it does not enjoy any clear monotonicity property with respect to A. For all these reasons, the approach used in the underlay setting does not work in the overlay scenario, and globally solving (29) with an affordable complexity appears to be a challenging task. In the coming section IV-C, we will trade-off performance with complexity, providing two sub-optimal, low-complexity algorithms.…”

“…As already mentioned, directly using fractional programming to solve (29) would result in a prohibitive complexity. For this reason, in the following we will resort to the tool of sequential fractional programming.…”

Device-to-device meets LTE-unlicensed

“…Typically, this is achieved with the high density of mobile user equipments (UEs) and allowing multi-hop transmissions of delay tolerant data between the UEs. The potential advantages of D2D communications include throughput enhancement, UE energy saving [2], and coverage expansion. The economic attraction to mobile operators is that significant capacity and coverage gains can be achieved without having to invest in network-side hardware upgrades or new cell deployments.…”

“…If the energy level is over the CCA energy threshold, the D2D UE waits for a random period, before it performs another CCA. After the COT has elapsed, if the UE wants to continue transmitting, it has to repeat the CCA process 2 . This entire process is illustrated in Fig.…”