The Multiple Power Allocation Strategy Research Based On The Sensing/Transmission Frame Structure For Cognitive Radio

Nowadays,with the increasing of wireless communication users,it highlighted the phenomenon of shortage of spectrum resources and the and the low utilization of spectrum,therefore,the study of cognitive radio communication is becoming increasingly important.Cognitive radio communication technology can be used to solve these problems,firstly,the device parameters can be changed in real time,so that the secondary user(SU)may dynamically access and timely departure of authorized bands,consequently improving the frequency utilization.Secondly,in cognitive radio,according to the sensing results,the transmission power can be flexibly assigned,while meeting the needs of authorized users(PU),the benefits of cognitive communication system can be maximized.So,cognitive radio technology to become the current hot research direction,and the further research is also the requirement of each user.Based on the aforementioned cognitive radio technologies,following work has been done in this thesis:(1)Under the traditional perceptual frame structure,the frame structure is divided into the sensing time slot of the frame front end and the transmission time slot of the back end of the frame.Among them,the role of the sensing time slot is enabling the secondary user to fully detect the signal of the authorized user,so as to obtain more accurate authorized information.The role of the transmission time slot is enabling the secondary user to access the frequency band and transmit data,to enhance the data transmission.However,both of them are mutually restricted relationship,therefore,there is a tradeoff between the allocation of the two parties.Under the sensing / transmission frame model of this paper,by using the special decoding device of secondary user receiver,the synchronization of secondary user sensing and transmission is realized,also the time slot of sensing and the time slot of the transmission slot are added to the maximum frame length T.(2)Under the traditional two power allocation strategy,it is assumed that authorized user does not change in the whole frame structure,thus,when authorized user is perceived to be busy by secondary user,the secondary user uses a lower transmission power p1;when authorized user is perceived to be idle by secondary user,secondary user uses a higher transmission power p0.But the possibility that authorized user is changing in a frame structure at any time,if secondary user access to higher power,it is possible in the state of authorized user from idle to busy,secondary user to form a greater interference effect;if the secondary user is connected with a lower power,the secondary user does not make full use of the channel when the state of the authorized user turns from idle to busy.For the purpose of taking into account both,we propose a four state power allocation strategy based on the sensing / transmission frame structure,so as to achieve the purpose of improving system throughput.At the end of the thesis,we verify the feasibility of the new model by computational simulation,and the proposed model is compared with the traditional model,at the same time,the influence of PU activity on the system is also considered.