Research On Statistical Priority-based Multiple Access Technology For High Time-sensitive Services

Under the conditions of modern over-the-horizon war,both armies outside the line of sight,identify and intercept the target through the detection device,and employ the medium-range and long-range guided weapon to launch the attack.To achieve weapon coordination,first enemy launch and long-range precision strike,the tactical data link network must be able to support the reliable transmission of high-time sensitive services.For instance,the primary design goals of the US military's advanced Tactical Targeting Network Technology(TTNT)are self-organizing interconnection of weapon platform and ultra-low latency information distribution.Its design philosophy is “speed kills the enemy”(quick information distribution and efficient cooperative control of the enemy).This data link system adopts a combination of frequency hopping and time hopping in physical layer,and Statistical Priority-based Multiple Access(SPMA)in MAC(Medium Access Control)layer.However,due to the confidentiality of military technology,although researchers can understand some of the characteristics and performance indicators of TTNT from the open literature,they cannot further acquire its complete technical details.In view of this situation,this paper studies the statistical priority-based multiple access technology for high time-sensitive services.The main contributions are summarized as follows:(1)A design method of frequncey hopping and time hopping patterns in physical layer for statistical priority-based multiple access is studied.Firstly,according to the length of the data frame,the network time is divided into a series of fixed-length time frames.The network time frame is further divided into a certain number of pulse time slots on the basis of physical pulse format.Then the frequency hopping sequence is constructed,extended and equalized based on the truncated prime number sequence.Afterwards,the frequency points of the frequency hopping sequence are allocated to “time-sequence” matrix,so that the transmission pulses are randomly separated in frequency and time.The rows and columns of the obtained preliminary matrix are randomly arranged and the frequency points are completely arranged to derive the final frequency hopping and time hopping patterns.Based on the design method,this paper gives two specific implementation examples of frequency hopping and time hopping patterns combining with the actual design parameters.By analyzing the Hamming correlation,frequency point collision and uniformity of the patterns,the analysis results demonstrate the effectiveness of the proposed design method of frequency hopping and time hopping patterns.(2)Based on the above-mentioned frequency hopping and time hopping design in physical layer,we study the statistical priority-based multiple access protocol for high time-sensitive services.The protocol first allocates frequency hopping and time hopping patterns to the node according to the network scale and the requirement of service transmission.The node detects the occupancy of the pulse time slot in each set of frequency hopping and time hopping pattern by means of listenning to the channel then derives the occupancy value of the logical channel.According to the proportion of various priority services,the sending measuring method is adopted to calculate the sending threshold of each priority service.At the beginning of each network time frame,the sender sequentially checks whether there is a data packet to be sent in the queue of network layer in terms of the priority order,and compares the service occupancy value of the frequency hopping and time hopping pattern with the sending threshold of priority service.If the occupancy value is less than the occurrence threshold,the node can send the data packet of the priority according to the frequency hopping and time hopping pattern of receiving node.The simulation results show that,compared with the traditional access protocol based on carrier sense multiple access/collision avoidance(CSMA/CA)in ad hoc networks,the protocol has great advantages in network throughput,packet delivery rate and average end-to-end delay and supports the transmission of high-time sensitive services reliably.