基于自适应随机接入的动态 D2D 发现资源分配机制

现有终端直通（device-to-device，D2D）中用户发现成功率低、发现范围小以及不能满足不同用户优先级的业务需求，针对上述问题，提出一种基于自适应随机接入的动态D2 D发现资源分配机制。该机制中具有高优先级的D2 D用户采用传统的随机接入方法向基站发送紧急请求信息；基站根据发送紧急请求信息的高优先级D2 D用户数，构建下一发现周期的发现资源分配信息。根据未成功选择发现资源块的次数，低优先级的D2 D用户自适应的在多信道时隙ALOHA（additive link on-line Hawaii system）和具有能量感知的多信道ALOHA接入机制之间进行切换。D2 D用户根据接收端的信干噪比大小，判断是否成功发现。系统级仿真结果表明，提出的机制与传统的随机信道接入机制相比，不仅能够满足不同优先级用户的业务需求，还能支持更高的发现成功率和更远的发现范围。

Dynamic D2D discovery resource allocation scheme based on adaptive random access

The existing device-to-device (D2D) discovery scheme in D2D communication has low discovery success ratio,small discovery range, and cannot satisfy the traffic requirements of D2D uses that have high priority, and in order to resolve this problem, this paper proposes a dynamic D2D discovery resource allocation scheme based on adaptive random access. Firstly, the users with high priority send an emergence request message to the base station based on traditional access random procedure, and then the base station configures the discovery resource allocation information of next discovery duration based on the number of emergence request message which is transmitted by D2D users who have high priority.Moreover, the users with low priority adaptively switches the random access from multichannel slotted ALOHA (MCALOHA) to energy sensing MCALOHA (MCALOHA-ES) based on the number of unsuccessful resource selection of D2D users who have low priority. Finally, D2D receivers estimate whether to discover its neighbor users successfully based on the received signal to interference plus noise (SINR). System simulation shows that the proposed schemecan not only can satisfy the traffic requirements of different priority users, but also support higher discovery success ratio and longer discover range compared to the conventional random access scheme.