We used the TETRA signal release 1 [specification 390 392–2; European Telecommunications Standards Institute (ETSI), Sophia-Antipolis Cedex, France], which comprised a time-division multiple-access frame structure with four time slots per frame on a single carrier.
Besides, frame construction, multiple access, bandwidth request and grant, scheduling, radio resource management, and QoS management are also part of the common part sublayer.
Figure 5 The multiple access game in strategic form.
In this multiple access communication system, all transmitters that want to send a data frame are required to transmit a request-to-send (RTS) frame to their intended receiver, which is then responsible for coordinating the packet transmissions among the competing transmitters.
Figure 6 Relationship between frame error rate and number of users for -ary DPPM with receive diversity, and a frame length of 128 bits over an AWGN channel,, SNR = 8 dB. Figure 7 gives the multiple access FER of -ary DPPM and -ary PPM over Nakagami fading channels with receive diversity.
Figure 1 The multiple access relay channel model.
PHY package is a program collection which is responsible for the physical layer functions corresponding to the real world, the main capability is using the frame structure form to provide link capacity, and the modular function includes the various wireless technical frame structures, such as orthogonal frequency division multiple access (OFDMA), and subcarrier permutation mechanism.
In the proposed scheme, the inverse matrix can be calculated in the arrival order of CSI feedback frames from each user in a time-domain multiple access (TDMA) manner, resulting in reduced overhead for the transmit beamforming weight computation.
A sensor may initiate frame transaction in different contention-based access phases using carrier sense multiple access with collision avoidance (CSMA/CA) and Slotted Aloha.
