Abstract-Device-to-device (D2D) communication is proposed as a vital technology to increase the system capacity and spectral efficiency, while reducing the latency and energy consumption. Existing researches usually investigate the resource allocation for D2D communications underlaying the orthogonal frequency division multiple access (OFDMA) based cellular network, un der the scenario in which spectrum can be spatially reused. However, most of these researches did not consider individual power constraint of each D2D device (e.g. a smart phone), which is generally limited for every device. Therefore, with the consideration of the transmit power limitation per device, the resource allocation issue is investigated in this paper for the multiple D2D pairs underlaid OFDMA-based cellular system with the target of achieving the optimal system throughput. By exploring the relationship between the number of sub carriers per D2D pair and maximum power constraint for each D2D pair, a sub-optimal joint power and subcarrier allocation algorithm is proposed to achieve high spectral efficiency with low complexity. Simulation results demonstrate that the performance of the proposed algorithm is very close to the optimal solution obtained by global exhaustive searching method. Meanwhile, the effect of number of subcarriers allocated to each D2D pair on the system performance is analysed through simulation results. Index Terms-Device-to-Device(D2D), resource allocation, inter-cell interference management. The tremendous growth of multimedia applications (e.g. huge video content delivery) in todays' wireless systems leads to high data rate requirement for future wireless mobile networks. Device-to-device (D2D) communication in cellular networks, called cellular D2D communication, has been con sidered as one of the key technologies to increase user data rate and network throughput, while reduce latency and energy consumption for data transmission. Unlike the traditional D2D communication system via WiFi and Bluetooth using unlicensed spectrum, the cellular D2D communication allows two users in proximity to form a D2D pair and communi cate with each other directly by using the licensed spectrum under the assistance of the base station (BS). Therefore, the quality of service (QoS) in the cellular D2D communication could be guaranteed. Also, new proximity-based services (e.g. advertisement, content sharing) can be added to the cellular network as well as offtoading the existing traffic from BS [1] . Two cellular spectrum sharing modes have been addressed for cellular D2D communications [2]: 1) orthogonal shar ing: the communication for each D2D pair is allocated with dedicated licensed spectrum. In other words, the spectrum is not shared within a cell; 2) non-orthogonal sharing: the licensed spectrum can be shared by both D2D and cellular links. Therefore, intra-cell interference exists. Mode selection between orthogonal sharing and non-orthogonal sharing was adequately studied in [3]- [5] . Under both spectrum sharing modes, resource allocation, including power and spectrum allocation, is very important for achieving high spectral effi ciency for cellular D2D communications [2]- [8] . Compared to the orthogonal sharing, a proper resource allocation for non-orthogonal spectrum sharing can generally achieve better spectral efficiency and energy efficiency [2] . The advantage of the orthogonal sharing is that the resource allocation is much simpler than that for the non-orthogonal sharing as only the channel status information (CSI) of D2D links are needed, while the CSI is needed for all the channels between any two devices. Both modes are considered in cellular networks as each mode has its unique advantage. In current cellular networks, orthogonal frequency division multiple access (OFDMA) [9]- [12] has been widely adopted for multiuser data transmissions. Based on the character inherited from orthogonal frequency division multiplexing (OFDM) which can transform the frequency selective fading channel into multiple flat fading subchannels or chunks, high system throughput can be achieved by exploring multi-user diversity when allocating the subcarriers/chunks to multi ple users adaptively [9]-[12]. Resource allocation schemes have investigated for both D2D spectrum sharing modes in OFDMA-based cellular networks [2] , [4]-[8]. In [2] , the effect of the transmission distance of the D2D link on the energy efficiency was investigated under the power constraint for both sharing modes. Based on the proximity characteristic of D2D communications, precious spectrum can be reused by multiple D2D pairs in one cell to improve the spectral efficiency of the cellular network. Therefore, most researches on resource allocation for D2D communications focus on the non-orthogonal spectrum sharing. [4] focused on the condition of enabling a D2D communication. In [4] , under a power control, D2D communication is enabled only when the path loss between a D2D pair is less than a threshold. [5] investigated how to allocate the transmit power when one D2D pair can share the same subcarrierlchunk with one cellular user. [6] , [7] and [8] extended the resource allocation to a scenario that subcarriers/chunks can be reused among multiple D2D pairs. Among all these researches, although the OFDMA system was addressed, the investigation of power control was limited in two scenarios. In the first scenario, 978-1-4673-643 2-4/15/$31.00 ©2015 IEEE 2955
An efficient resource assignment scheme for multiple D2D pairs with the objective of maximizing the total system capacity was studied in REF .
Resource allocation for multiple-pair D2D communications in cellular networks
2015 IEEE International Conference on Communications (ICC)
2015 IEEE International Conference on Communications (ICC)
Computer Science