Research On Distributed Reservation Hybrid Multiple Access Control Technology

With the gradual evolution of wireless networks,multi-user,high-rate,low power,differentiated and intelligent communication have become the important factors in the design of distributed multiple access protocols.Hence,how to design an efficient MAC protocol in the pluralistic and heterogeneous networks has aroused great concern in today's industry and academia.As is well known,the IEEE 802.11 standards that are regarded as the mainstream Medium Access Control(MAC)protocols have been accepted and widely applied in the Wireless Local Area Network(WLAN)due to its low complexity,low cost,and high data rate.However,with the diversification and complication of wireless networks,the contention-based distributed MAC protocol is facing severe challenges in terms of access efficiency,transmission reliability,and energy consumption.Based on this,we mainly focus on the distributed multiple access technologies with the evolution of wireless networks in this thesis.The related work and contributions are summarized as follows:1.To solve the low efficiency,the high collision and the packet loss problems of random access in the dense deployment distributed networks,a time-slot reservation-based medium access control,called TR-MAC,is proposed.In TR-MAC,the negotiations and the data communications are separated through the control sub-frame and the data sub-frame,and then the multiple collision-free data transmissions in the data sub-frame can be reserved by handshake in the control sub-frame.Therefore,TR-MAC can adapt to the dynamic changes of the network and provide the quality of service(Qo S)for data transmissions.Besides,an enhanced Markov chain is modeled to analyze the throughput performance of the proposed TR-MAC protocol,and the optimization problem is formulated to maximize network throughput.2.To solve the strong communication interference and low data transmission efficiency problems that are caused by using the fixed transmission power during the period of negotiations and data communications,a power-control with time-slot reservation-based MAC is proposed,namely PTR-MAC.It allows the users to jointly reserve the transmission power and slot resources as the handshake commencing,so that the users can complete the data communications with the minimum transmission power,reduce communication interference and achieve parallel transmission.Therefore,the channel utilization can be greatly improved.Furthermore,the upper bound of slot utilization and the throughput performance of PTR-MAC are analyzed,and then the overall throughput of the network is maximized by solving the optimization problem.3.To further improve the communication capacity,a channel with time-slot reservation MAC is proposed,namely CTR-MAC,which extends the single-channel communications into multi-channel communications.With the combination of multi-channel and slot reservation,the multiple channels and slot resources can be reserved via the common control channel,thereby immeasurably improving the capability of parallel communications.Moreover,based on the presented Markov model in Chapter 2,the throughput performance of CTR-MAC is analyzed,and the parameters is optimized to maximize the network throughput.4.To solve the multiple access problems in the backscatter communications,a distributed reserved MAC is applied to the backscatter communications that are relying on the Wi-Fi architecture.By introducing the full-duplex technology,the energy-harvesting technology and the distributed reservation scheme to achieve the ultra-low-power backscatter communications.Intuitively,Wi-Fi communications and backscatter communications are separated via Wi-Fi access points(APs)without interference.When the backscatter communications commence,Wi-Fi stations(STAs)terminate the communications,the backscatter devices(BDs)perform the handshaking and reserve the future multiple backscatter transmissions via the AP's excitation signal,thereby improving the channel access.Noted that each BD harvests energy during the period of Wi-Fi communications.In addition,the network performance is analyzed based on the proposed Markov model,and then the optimization problem is formulated to maximize the overall throughput.5.To solve the problem of fair sharing between LTE-LAA and Wi-Fi in the unlicensed band,the full-duplex technology is first introduced into LTE-LAA/Wi-Fi coexistence networks to propose coexistence MAC.It enables Wi-Fi users to sense while transmitting,i.e.,Wi-Fi users can communicate while sensing the channel,and thus effectively alleviating the collisions and improving channel utilization.Besides,based on the enhanced Markov models with considering the sensing errors,the throughput of LTE-LAA and Wi-Fi can be analyzed respectively.Secondly,to ensure the privilege of Wi-Fi users on the unlicensed band and mitigate the interference from LTE-LAA,the distributed reserved MAC combined with full-duplex is further applied to LTE-LAA/Wi-Fi coexistence networks.By using the distributed reservation mechanism,multiple transmissions opportunities can be achieved by Wi-Fi users.Therefore,the effective access of Wi-Fi users is guaranteed and the overall performance of the LTE-LAA/Wi-Fi coexistence network is improved.