Dynamic channel reservation scheme based on priorities in LEO satellite systems

According to low earth orbit（LEO） satellite systems with users of different levels, a dynamic channel reservation scheme based on priorities is proposed. Dynamic calculation of the thresholds for reserved channels is the key of this strategy. In order to obtain the optimal thresholds, the traffic is predicted based on the high-speed deterministic movement property of LEO satellites firstly. Then, a channel allocation model based on Markov is established. Finally, the solution of the model is obtained based on the genetic algorithm. Without user location, this strategy effectively reduces handover failures and improves channel utilization by adjusting dynamically the thresholds according to traffic conditions. The simulation results show that the system＇s overall quality of service can be improved by this strategy.

Dynamic random channel reservation protocol

Demand assignment MAC protocols have been used widely in wireless networks. It can effectively utilize wireless bandwidth. Some strategies can he used by demand assignment MAC protocols to further improve their efficiency. The concept of transmit probability is introduced. This concept allows a request slot to be assigned to many different traffic classes at the same time. Based on it, the dynamic random channel reservation （DRCR） protocol is proposed. The DRCR protocol operates dynamically by observing the traffic conditions. It uses information about the recent traffic conditions to assign transmit probability with which an mobile station can select request slots with lower traffic. The performance of DRCR is evaluated and compared with RSCA. The results show that DRCR is more stable than RSCA, it offers shorter delays of requests than RSCA and can relieve heavily stressed traffic classes faster than RSCA.

Learning-Based Admission Control for Low-Earth-Orbit Satellite Communication Networks

Satellite communications has been regarded as an indispensable technology for future mobile networks to provide extremely high data rates,ultra-reliability,and ubiquitous coverage.However,the high dynamics caused by the fast movement of low-earth-orbit(LEO)satellites bring huge challenges in designing and optimizing satellite communication systems.Especially,admission control,deciding which users with diversified service requirements are allowed to access the network with limited resources,is of paramount importance to improve network resource utilization and meet the service quality requirements of users.In this paper,we propose a dynamic channel reservation strategy based on the Actor-Critic algorithm(AC-DCRS)to perform intelligent admission control in satellite networks.By carefully designing the longterm reward function and dynamically adjusting the reserved channel threshold,AC-DCRS reaches a long-run optimal access policy for both new calls and handover calls with different service priorities.Numerical results show that our proposed AC-DCRS outperforms traditional channel reservation strategies in terms of overall access failure probability,the average call success rate,and channel utilization under various dynamic traffic conditions.

Performance Analysis of Channel Assignment with Prioritized Handoff Procedures in GSM

A mathematical model of channel assignment with prioritized handoff procedures is given according to the physical handoff process in GSM networks with some reasonable simplifications and assumptions, and a numerical calculation is applied to the model. A simulation model is established to verify the results of the mathematical model. The results show that the overall loss probability is increased with the number of channel reservation increasing, although the probability of forced termination can be reduced. Therefore, three queuing schemes are proposed: (1) queuing for handoff calls without channel reservation, and the queuing rule is “First come, first served”; (2) queuing for handoff calls without channel reservation, and the queuing rule is “First come to the threshold, first served”; (3) queuing for new calls with one channel reserved for handoff calls. Simulations are also made for the three queuing schemes, the results indicate that the third one is the best, and it is also easy to realize. The optimal queuing length and the maximum waiting time are suggested for the third scheme.

A New Exposed-terminal-free MAC Protocol for Multi-hop Wireless Networks

This article presents a new multichannel medium access control (MAC) protocol to solve the exposed-terminal (ET) problem for efficient channel sharing in multi-hop wireless networks. It uses request-to-send and clear-to-send (RTS/CTS) dialogue on a common channel and flexibly opts for conflict-free traffic channels to carry out the data packet transmission on the basis of a new channel selection scheme. The acknowledgment (ACK) packet for the data packet transmission is sent back to the sender over another ...