基于碰撞稀疏化的定向移动自组织网络高效多址接入研究

Directional wireless mobile Ad Hoc network (D-MANET) is one of the important component of 5G networks. The distinguished feature of directional data transmission and reception brings many benefits while makes the directional nodes difficult to sense and detect the collisions of the concurrent links. The density scenarios of the D-MANET caused by the distributed structures and mobility of nodes, make it more difficult to sense and detect the collisions of the concurrent links. In this project proposal, a novel collision scattering idea is proposed, which scatters the collisions between the concurrent links by increasing the number of time-frequency resource blocks (RB). A new concept named RB efficiency is proposed to evaluate the benefits and overhead of the collision scattering based multiple access control protocol, which omits the impacts of the physical layer. And the RB efficiency is found to be a function of the RB number and the number of concurrent links, such that a new problem to optimize the RB efficiency is proposed, which can be the theoretical guidance to the distributed network resource allocation. In this project, the collision probability will be modelled and analyzed firstly, based on which the RB efficiency will be optimized. Then, a collision scattering and Push-Pull cascading based scheme will be designed and optimized to allocate the RBs to multiple concurrent links. Finally the frame of the directional multiple access control (MAC) protocol and the adaptive collision scattering scheme will be designed. This project will study and explore the new theory of collision scattering, and provide theoretical guidance to design multiple carrier based MAC protocols, such as OFDMA and FDMA.

定向移动自组织网络(D-MANET)是5G网络的重要组成部分。定向数据收发在带来诸多裨益的同时，也使得定向节点难以侦听和感知到网络中其他并发链路的干扰，而D-MANET的分布式无中心特性和节点移动性所造成的高密集网络使得并发链路间的冲突更加严重和难以避免。本项目提出碰撞稀疏化的新思想，通过增加承载数据包的时频资源块(RB)个数稀疏化并发链路间的碰撞；提出RB利用率的新概念，衡量忽略物理层影响时基于碰撞稀疏化的多址接入协议所带来的收益和开销；提出基于碰撞稀疏化的RB利用率最优化的新问题，建模分析基于碰撞稀疏化的单链路碰撞概率并优化RB利用率，提出基于碰撞稀疏化与Push-Pull级联的分布式网络资源分配新方法，设计基于碰撞稀疏化的多址接入框架和自适应碰撞稀疏化优化机制。探索基于碰撞稀疏化的新理论，为设计基于OFDMA、FDMA等多载波定向多址接入提供理论指导。

定向波束在为定向移动自组网带来波束传输距离远、干扰范围小等优势的同时，也带来了难以感知和避免与周边并发传输链路冲突的问题，该问题在分布式网络或因移动而造成的密集网络中变得尤为严重且难以避免。本项目提出了碰撞稀疏化的研究思想并设计出了相应的资源分配算法和多址接入协议，通过采用OFDMA、FDMA等多载波技术增加承载数据包的时频资源块(RB)个数，将相同空时频碰撞域的并发传输稀疏化到基于不同RB的碰撞域，降低碰撞概率提高资源利用率，扩展了定向移动自组网的应用场景和领域。.从理论层面研究了基于随机竞争的定向并发传输时是否感知并发链路干扰的两种情况，包括无感知时基于碰撞稀疏化的和基于双向载波侦听与碰撞稀疏化相结合的情况，和有感知时基于调度的和基于碰撞稀疏化的情况。研究发现：(1)无感知时最大化RB利用率的条件是参与竞争的定向链路个数等于RB个数；(2)无感知时双向载波侦听与碰撞稀疏化相结合可优势互补，不仅可利用载波侦听降低同一扇区和背向扇区中请求帧的冲突概率还可利用碰撞稀疏化降低应答帧的冲突概率；(3)提出了一种基于团的集中式算法可计算有感知时碰撞稀疏化增益的上限；(4)有感知时先将用户分组再将资源分配给用户分组，可约束和控制并发传输的碰撞域大小和规模、提升网络性能。.从应用层面研究了数据传输协议、分布式资源分配算法和自适应多址接入等技术。研究发现：(1)无感知时以稀疏化序列分配资源可降低并发链路冲突；(2)无感知时根据节点的收发状态对时隙分类并重分配可提高资源利用率；(3)基于统计和估计的并发链路冲突概率可推导计算出并发传输链路个数，进而采用“参与竞争的定向链路个数等于RB个数”准则分配资源可最大化资源利用率；(4)基于Push-Pull级联和二分树的碰撞稀疏化资源分配算法，可将被冲突的时隙通过二分重分配从而提升资源利用率；(5)基于对无线传输环境和业务模型的感知信息，可采用调整信道接入参数、传输参数以及信道接入方式的方法达到自适应碰撞稀疏化的目的。