Research On Spectrum Cognition And Carrier Aggregation Technology Based On Wireless Ad Hoc Network

The wireless ad hoc network has been widely used in various fields due to their fast and flexible networking,dynamic topological structure changes,multi-hop,and strong survivability,such as military communications,disaster relief,sensing,and monitoring.Wait.With the continuous expansion of the size of the ad hoc network and the increasing demand for node services,mobile data traffic has grown exponentially.In order to improve the node's transmission rate and system capacity,a large number of spectrum resources are urgently needed to solve this problem,but it is difficult to find a continuously available large-bandwidth spectrum in an environment with severe electromagnetic interference.The carrier aggregation technology proposed by 3GPP can increase system bandwidth by aggregating multiple continuous or discrete frequency bands,thereby achieving faster data transmission rates and higher spectrum utilization.In order to implement the carrier aggregation technology,the state of the spectrum needs to be recognized first to determine the spectrum availability.In scenarios where there are a large number of frequency points to be measured,existing research schemes use a single node to complete the recognition of all frequency points.This solution leads to long cognitive time and low cognitive accuracy,which cannot meet the requirements of time delay and accuracy.Therefore,three schemes are proposed to improve the above problems: spectrum recognition based on frequency correlation,multi-node recognition based on node correlation and consistency of multi-node spectrum recognition.Simultaneously model and analyze and compare the delay and cognitive accuracy of the above three schemes.The analysis results show that the first two schemes can reduce the delay,especially the second scheme,which has the advantage of delay when there are many cognitive frequency points,but the cognitive accuracy is slightly reduced.The third scheme increases latency overhead but improves cognitive accuracy.For the latter two schemes,the value range of the number of nodes,the number of cognitive times and the number of frequency points under the constraints of time delay and cognitive accuracy are also analyzed.In the third scheme,the comprehensive influence of the number of neighbor nodes on the consistency convergence speed and the selection of the optimal number of neighbor nodes are studied.After obtaining the spectrum availability information,effective resource allocation to the nodes in the network before carrier aggregation can improve network throughput performance.Existing studies are based on one-hop cellular networks.The multi-hop characteristics of ad hoc networks is considered.The established model is based on the three-hop frequency reuse mechanism and it needs to meet the minimum transmission rate requirement of each node.In order to maximize the network throughput,the component carrier,resource block and modulation and coding scheme are jointly allocated.The model can be transformed into a 0-1 integer linear programming problem and the branch implicit enumeration algorithm is designed to solve it.The effects of different frequency bands,number of nodes,component carriers,and network environment on system throughput are analyzed,and the spectral efficiency of multi-band and single-band is compared.The results show that in the ad hoc network environment,a higher throughput is obtained due to the multiplexing mechanism,and the solved algorithm can meet the minimum transmission rate requirements of each node.The self-organizing network is based on the 802.16 d protocol,and the carrier aggregation implementation process under this protocol is different from the existing carrier aggregation implementation process based on the TS36.213 protocol.According to different aggregation methods,two schemes are proposed,namely,zero-padded broadband aggregation and radio frequency aggregation,and the effect of the spacing between component carriers on the system bit error rate is analyzed.Aiming at intra-band carrier aggregation scheme,this paper selects Zynq series chip to realize.In FPGA boardlevel test,the verification of the carrier aggregation function is completed,and good bit error performance is achieved.