Power Optimization in Multimedia Sharing in Device to Device Communication Underlaying Cellular Networks

In underlay device-to-device (D2D) communication, a D2D pair reuses the cellular spectrum and creates interference to regular cellular users. Optimal operation requires joint consideration for the achieved D2D rate and the added interference to cellular users. Most existing work on D2D rate maximization concerns only the simplified scenario where the D2D pair has access to a single channel or resource block. In this work, we present an optimization solution to allocate the D2D transmission power over multiple channels, to maximize the sum rate between D2D and cellular users, under a sum-power constraint on the D2D transmitter and minimum SINR guarantees at each RB for all cellular users. The proposed optimization is applicable to both uplink and downlink cellular spectrum sharing. Our simulation studies further shed light into how the maximum sum rate is impacted by the available D2D power and the SINR guarantees.

The most precious resource for the mobile network operators (MNOs) is the radio spectrum, cardinal for meeting the quality of service (QoS) requirements of the users. An integral technology of the budding fifth generation (5G) wireless communication networks (WCNs) is device-to-device (D2D) communication. To make use of the gains offered by D2D communication, optimal resource sharing with the cellular users in the network is necessitated. This paper proposes an adaptive resource block (RB) allocation scheme, using Hidden Markov Model (HMM), to assure adequate resource availability to each demanding D2D pair in the network. The adaptive allocation of resources improves the system throughput and energy efficiency (EE), meeting the QoS demands of the D2D pairs and fostering green communication. Since RB sharing is between pairs and cellular users, interference rises. The improvement in performance is achieved by sectoring the cellular coverage region, which diminishes the interference levels. The potency of the proposed adaptive scheme has been verified through simulations.

In the paper, the distributed joint spectrum sharing and power allocation scheme is proposed to improve the local services in the Device-to-Device (D2D) communication underlaying cellular networks (CNs) with limited signaling overhead. The scheme aims to optimize the throughput of D2D communications over the shared uplink frequency spectrum meanwhile the base station (BS) protects the cellular users (CUs) from the interference of D2D users. Stackelberg game (SG) is formulated to model the problem for deriving the distributed scheme. In the game, the BS, as a leader, coordinates the interference from the D2D users to the cellular uplinks and maximizes its own profit by pricing the interference. On the other hand, D2D pairs, as followers, compete for the spectrum as a Nash non-cooperative game to maximize their own data rates individually. The pricing mechanism at the BS converging to the Stackelberg Equilibrium is studied. Finally, numerical examples are presented to verify the proposed scheme. It is shown that the scheme is effective on the resource allocation and the CU protection with limited signaling overhead.

Device-to-Device (D2D) underlaying communication system may be the solution to increase system data rate and reduce the workload of eNodeB. This communication system shares the same resources to two types of user, the cellular users and D2D pair. However, by using same resources, D2D underlaying communication system will increase the interference level among users. To overcome this problem, a good allocation algorithm is needed to allocate Resource Blocks (RB) which used by Cellular User Equipment (CUE) and D2D simultaneously. This work assumes all CUEs will use the RB first. The D2D pairs RB allocation take place after all CUEs get the resource. A modified Joint-Greedy algorithm is proposed to improve D2D pairs RB allocation process. The algorithm consist of two main phase. In the first phase, all D2D pairs will choose the best RB on the system, that being used by the CUE, and take that RB as a candidates. In the second phase, the eNodeB (eNB) will decides which of these candidates that will be allocated to D2D pair by searching the minimum impact of each CUE. From the simulation process, system with underlaying D2D communication can increase the system spectral efficiency system by 30%. Modified Joint-Greedy algorithm allocates can improve spectral efficiency of the system by 3.059% compared with mean-greedy allocation algorithm and 4.33% compared with a conventional greedy algorithm.

For the downlink device-to-device (D2D) communication underlaying cellular networks, we study the resource allocation policy which jointly optimizes the resource block (RB) assignment and the powers of D2D users and cellular users. Aiming to improve the sum-rate of D2D subsystem and ensure the quality of service (QoS) of the cellular networks, a nominal optimization problem is formulated. Furthermore, considering the uncertainty in channel state information (CSI), a worst-case robust optimization problem with ellipsoid uncertainty set is investigated. After transforming the non-convex problem into a convex subproblem, we obtain the closed-form solution of the subproblem by using Lagrangian dual method and Karush-Kuhn-Tucker (KKT) conditions. And the optimal solution of the original problem is obtained by one dimensional search algorithm. The simulation results verify the advantages of the proposed resource allocation policy and illustrate the effect of the robustness in D2D communication system.

For device-to-device (D2D) communication under laid in a cellular network with uplink resource sharing, both cellular and D2D pairs may cause significant inter-cell interference (ICI) at a neighboring base station (BS). In this paper, under optimal BS receive beamforming, we jointly optimize the power of a cellular user (CU) and a D2D pair for their sum rate maximization, while satisfying minimum SINR requirements and worst-case ICI limit in multiple neighboring cells. We solve this non-convex joint optimization problem in two steps. First, the necessary and sufficient condition for the D2D admissibility under given constraints is obtained. Finally, we consider joint power control of the CU and D2D transmitters. We propose a power control algorithm to maximize the sum rate. Depending on the severity of ICI that D2D and CU may cause, we categorize the feasible solution region into five cases, each of which may further include several scenarios based on minimum SINR requirements. The proposed algorithm is optimal when ICI to a single neighboring cell is considered. For multiple neighboring cells, we provide an upper bound on the performance loss by the proposed algorithm and conditions for its optimality. We further extend our consideration to the scenario of multiple CUs and D2D pairs, and formulate the joint power control and CU-D2D matching problem. We show how our proposed solution for one CU and one D2D pair can be utilized to solve this general joint optimization problem. Simulation demonstrates the effectiveness of our power control algorithm and the nearly optimal performance of the proposed approach in the setting of multiple CUs and D2D pairs.

Two-stage coalition formation and radio resource allocation with Nash bargaining solution for inband underlaid D2D communications in 5G networks

This paper analyzes a spectrum access scheme based on region division for Device-to-Device (D2D) communication underlaying cellular networks with outage constraint for cellular communication. The D2D pairs will access the spectrum by sharing the cellular uplink (UL) frequency resources in the networks. By utilizing stochastic geometry, D2D accessing the frequency spectrum can be modeled as the probability that the cellular user (CeUE) SINR is below an appropriate threshold. And the constraint of the probability appears as a transcendental equality, so we figure out the solution with the help of Lambert W function and obtain the closed-form solution of the region division in the whole cell when the cellular location are determined. Then in the simulation, we analyze the relationship between system capacity and key parameters including the CeUE location, the D2D density and D2D output power in detail. The results show that the proposed scheme can make the D2D pairs access the frequency spectrum in the networks effectively.

A novel energy-aware utility maximization for efficient device-to-device communication in LTE-WiFi networks under mixed traffic scenarios

With device-to-device (D2D) based relay-assisted communications, deep faded cellular users (CUs) get a better connectivity. The deep faded CU's achievable throughput of the link from base station (BS) to the CU is less than the rate demand from the CU (unsatisfied CUs). In this paper, we study the resource allocation problem for both CUs and D2D pairs to increase the achievable throughput. This is accomplished by reducing the difference between rate demand and rate achieved for the active CUs. The resource allocation optimization problem is solved in three steps. The initial set of resources that can be allocated to each active CUs is determined in the first step. In the second step, it finds the set of active CUs which needs D2D assistance and then it finds suitable D2D relay nodes (DRNs). Resource allocation to those DRNs and D2D pairs without degrading the link throughput of active CUs is performed in the third step. Numerical results shows significant amount of throughput gain for the active CUs using D2D communication. We also measure the performance of our proposed model in terms of churn rate and the number of excess resource blocks (RBs) in the system.

In this paper we propose an interference coordination mechanism to enhance the system capacity by mitigating the interference among cellular users and device-to-device (D2D) users. We consider the situation that one cellular user equipment (CUE) and two D2D pairs exploit the same resource blocks (RBs) in the uplink (UL) period. Considering the interference to signal ratio (ISR) of all kinds of users, this mechanism can select one CUE and two D2D pairs in one single cell sharing identical radio resources without causing intensive interference to each other. Numerical results show that we can effectively avoid the high interference among D2D pairs and cellular users so as to maintain the system capacity at a relatively high level.

We consider a cooperative device-to-device (D2D) communication system, where the D2D transmitters (DTs) act as relays to assist cellular users (CUs) in exchange for the opportunities to use the licensed spectrum. To reduce the overhead, we propose a novel two-timescale resource allocation scheme, in which the pairing between CUs and D2D pairs is decided at a long timescale and time allocation factor for CU and D2D pair is determined at a short timescale. Specifically, to characterize the long-term payoff of each potential CU-D2D pair, we investigate the optimal cooperation policy to decide the time allocation factor based on the instantaneous channel state information (CSI). We prove that the optimal policy is a threshold policy. Since CUs and D2D pairs are self-interested, they are paired only when they agree to cooperate mutually. Therefore, to study the behaviors of CUs and D2D pairs, we formulate the pairing problem as a matching game, based on the long-term payoff of each possible pairing. Furthermore, unlike most previous matching model in D2D networks, we allow transfer between CUs and D2D pairs to improve the performance. Besides, we propose an algorithm, which converges to an epsilon-stable matching.

This paper investigates the resource allocation design in device‐to‐device (D2D) communication underlying cellular networks, which is assisted by multiple intelligent reflecting surfaces (IRSs) deployed at the cell boundary to enhance desired signals and mitigate interference between D2D pairs and CUs. In this regard, a multi‐objective optimization problem (MOOP) framework is formulated to jointly maximize the downlink sum‐rate of the D2D pairs and cellular users (CUs). To doing so, the MOOP is first converted into a single‐objective optimization problem (SOOP) by invoking the weighted sum method. Next, to facilitate the high‐coupled non‐convex SOOP formulation, it is decomposed into two sub‐problems through the alternative optimization method. For the first sub‐problem, the inner approximation and successive convex approximations are adopted for jointly allocating D2D transmission power, subcarrier assignment, and transmit beamforming matrix at the BS. For the second sub‐problem, an iterative algorithm based on the penalty‐based method as well as Fenchel's duality approach is adopted to design the passive beamforming matrices at IRSs, which is guaranteed to rapidly converge to a stationary point. Simulation results reveal that a non‐trivial trade‐off between the total throughput of CUs and D2D pairs exist. Furthermore, the proposed framework significantly outperforms existing works addressed in the literature.

Device-to-Device (D2D) communications underlaying cellular networks can improve the network capacity and spectrum efficiency by sharing the cellular resources in the direct-transmission mode. However, the stringent interference between D2D and cellular systems can seriously repress the overall performance improvement. In this paper, we aim to solve this dilemma by applying the concept of differentiated priority into the resources sharing problem between the D2D pairs and cellular users. Firstly, we modified the conventional partial time-frequency resource allocation scheme to let each D2D pair select its sharing comrades, i.e. the cellular users, based on its own preference list such that less amount of mutually interference can be incurred. Secondly, the differentiated priority scheme is furthered implemented into the cellular users, i.e. the so-called bipartite differentiated priority. Then, the association problem between the D2D pairs and cellular users is solved by using the Gale-Shapley algorithm. The simulation results show that the proposed schemes can greatly enhance the system stability and capacity, while accommodating more D2D pairs.

We develop a joint spectrum sharing and power control strategy to increase the admissible number of device-to-device (D2D) links in an underlaying cellular network while guaranteeing the quality-of-service (QoS) of both D2D links and cellular users (CUs). The proposed spectrum sharing algorithm, termed as interference-filling (IF), examines whether the SINR requirements of all the existing CUs and D2D users can be met if a new D2D pair is admitted. In the sequel, two power control schemes are proposed to check the resultant interference level and increase the transmit power of the admitted D2D pairs group-by-group to further improve the system throughput. IF algorithm is based on the ordering statistics of the interference amounts from D2D transmitters to CUs, thus neither grid searching nor iteration is needed. Furthermore, the two proposed power control schemes are in closed-forms. These two favorable properties make the proposed strategy cost-effective and computationally efficient. Numerical results show the effect of the proposed IF and power control schemes in term of admissible D2D pairs and system sum rate.