# A Multiple Access Protocol Based on Gray Forecast for Satellite Network  
[PERSON]  
1 College of Computer, Nanjing University of Posts and Telecommunications, Nanjing 210003, China; [EMAIL_ADDRESS] (J.Z. ); [EMAIL_ADDRESS] (S.C.) Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks, Nanjing University of Posts and Telecommunications, Nanjing 210003, China College of Tongda, Nanjing University of Posts and Telecommunications, Yangzhou, 225127, China; [EMAIL_ADDRESS]  
1 May 2  
and apply satellite resource allocation strategies. Well-designed satellite network multiple access protocols should also be further investigated. Multiple access protocols involve user access and resource allocation to ensure the quality of service and maximize the use of satellite resources. The three main ways of multiple access protocols are based on fixed bandwidth allocation, random access and bandwidth allocation for demand assignment. In fixed bandwidth allocation, each terminal is allocated a certain amount of bandwidth. Because the channel allocation is static, this way cannot adapt to the change of source. Fixed bandwidth allocation easily causes throughput degradation in the case of more users, and the utilization rate is low in the case of fewer users [6]. For random access, it can satisfy the dynamic demand of channel resources in the case of low channel load, but in the case of higher channel load, more channel resources will be wasted because of the intensification of packet collisions. As the Aloha protocol, the packet in the transmission process may collide with the incoming packet at the next time and produce a delay. Although the possibility of collision is reduced by the allocation of the time slot in the improved time slot Aloha protocol [7; 8], the channel instability still has not been properly solved. In bandwidth allocation for demand assignment, the terminal or ground station sends the uplink to the satellite according to its own actual needs. It not only satisfies the user's demand for the actual bandwidth, but also does not waste the channel resources. However, due to the requirements of appointment and slot allocation, delay is the biggest problem. Therefore, in order for the data to be transmitted in a complete and orderly manner and to make the transmission delay as small as possible, the combination of the advantages of these three ways is typical. Frequency division multiple access (FDMA), time division multiple access (TDMA) and code division multiple access (CDMA) are based on the fixed allocation multiple access protocol. In fixed allocation, a user occupies a channel to transmit signals, and a specific physical channel is related to multiple access methods. For example, FDMA, TDMA and CDMA channel performance are associated with bandwidth, timeslot and pattern, respectively. Bandwidths, timeslots and patterns are three forms of multiple access channels [9]. In bandwidth-based demand assignment, satellite network multiple access protocols mainly include the combined free/demand assignment multiple access (CFDAMA) protocol [10] and the burst targeted demand-assignment multiple access (BTDAMA) protocol [11]. These two protocols are based on a classical TDMA approach. CFDAMA improves the frame structure of TDMA based on the demand assignment distribution and free allocation method. The principle of CFDAMA and BTDAMA considers a user's timeslot to apply the information about demand assignment allocation. Thus, the number of timeslots allocated to a user from a system with remaining timeslots is then allocated according to the requirements. These remaining timeslots are freely poll allocated to all active user terminals, and channel resource allocation is reasonable because these protocols have demand assignment and free allocation. The CFDAMA protocol can provide an enhanced communication system, but the communication delay remarkably increases with high service volume. The BTDAMA protocol separates user access requests from satellite resource allocations.