Joint Domain Based Massive Access For Small Packets Traffic Of Uplink Wireless Channel

Among the three categories of 5G scenarios,especially in the uplink scenario,a large number of applications such as blog,instant messaging,social networking,and over-the-top applications in the mobile Internet and large-scale Internet of Things will generate a huge mess of small packets.The small packet service faces two problems.One is that the information data in the small data packet is very short,the additional signaling required during each transmission is very large,which brings a lot of waste of system resources;the second is that the number of online users is huge in the network,and there will be much time delay in the process of multi-user detection.To solve above two problems,this paper proposes joint domain based massive access for small packets traffic of uplink wireless channel,realizing uplink grant-free access without signaling overhead,and enhancing the system's overload rate greatly.Specifically,the paper includes the following two aspects:1.When the user equipment only knows the amplitude or power gain of its own channel state,and the base station obtains the perfect channel state information of all user equipment,an uplink multiple access scheme combining joint time domain,frequency domain,code domain and power domain is proposed.In the scheme,the user equipment first pre-code the data signal to be processed so that all the shared time-frequency-space resource blocks can be used,and then transmit the data with corresponding transmission power based its own channel gain,and the receiver adopts interference cancellation based on orthogonal block matching pursuit algorithm(ICBOMP)to detect active users and demodulate signals.Simulations show that this access scheme can make the system achieve an overload rate of up to 300%on the basis of free signaling overhead.2.When the user equipment only knows the amplitude or power gain of its own channel state,and the base station has imperfect CSI,how to apply the above-mentioned joint domain non-orthogonal multiple access method is studied.A pilot is added before the frame data to be transmitted at the transmitting end,and the base station adopts a data-aided feedback channel estimation method for user detection and signal decoding.Simulations show that there is only a loss of 0.6 dB compared with ideal CSI and recovery algorithm at 300%system overloading.