Research On Deterministic Low Delay Based On Complementary TDD In UAV Assisted Internet Of Things

With the booming development of 5th generation mobile communication technology(5G),ultra-reliable and low-latency communications(URLLC),one of the three application scenarios of 5G,has received much more attentions.It mainly focuses on the high reliability and low latency of control information communication.However,the control information block length is generally short,which makes Shannon theorem no longer applicable in traditional communication systems.In addition,a new physical layer slot format relationship is proposed in 5G new radio(NR),which significantly reduces the length of a single time slot compared with Long Term Evolution(LTE),so there are also some studies on 5G NR slot format.Complementary Time Division Duplex(C-TDD)is a new technology proposed last year that uses complementary slot formats in carrier components to transmit data.It has great prospects in reducing communication network delay.On the other hand,an unmanned aerial vehicle(UAV)is regarded as an extremely efficient supplementary means to ground communication network due to its characteristics of high mobility,high controllability,and on-demand deployment.However,considering its own limited energy,energy consumption is the main problem affecting the performance of UAV communication networks.Summarily,to meet the trend of the era of Internet of things(Io T),this paper will use the UAV to support its ground Io T equipment as one kind of URLLC service and use the complementary TDD technology to effectively reduce the delay.We will focus on the research of resource allocation and management based on finite block length(FBL).The main contents and innovations of this paper are as follows:Firstly,from the aspects of time slot resource allocation and cross carrier scheduling in the protocol,this paper verifies the feasibility of complementary TDD,and verifies that it can effectively reduce the delay of communication network with the help of a soft baseband platform.Then,a model of applying complementary TDD to UAV communication networks is constructed.On this basis,a problem of minimizing communication delay is established,and its performance is verified by simulations.Secondly,this paper constructs a UAV relay communication network model providing URLLC services in a complementary TDD scenario.Since the main consideration is the communication of control information with short information codeword length,the model is established based on finite block length theory,and reachable rate and decoding error probability threshold are deduced;At the same time,the communication delay model in the complementary TDD scenario and the line of sight(Lo S)channel model with a specific probability caused by the particularity of UAVs are also established.Thirdly,considering that the limited energy of UAVs is the main problem affecting the system performance,we jointly optimize the associated scheduling of Io T equipment,bandwidth resources,deployment location and power control of UAV,to minimize the transmission power of UAVs.Under various constraints,a mixed integer nonconvex optimization problem is established.For this purpose,the block coordinate descent(BCD)method is adopted,and an effective iterative algorithm is proposed.In addition,the convergence of the algorithm is analyzed and explained.Different resource allocation schemes are used to calculate the minimum transmission power required by UAVs.Simulation results show that the iterative algorithm proposed in this paper can effectively improve the energy consumption of UAVs.