A common case in a cellular network is that the schedulers are operated at the base stations (BSs), so that the set of schedulers corresponds to the BSs and for each BS, the set contains all uplink and downlink links formed by the BS and the UEs served by it.
In addition, effective capacity concept has been used to model downlink wireless link delay.
In the nontransparent mode, each TDD frame is divided into downlink and uplink intervals, each of which is further divided into an access link interval for the MS (i.e., used for the BS-to-MS and RS-to-MS links) and a relay link interval for the RS (i.e., used for the BS-to-RS link) [8].
One, called Frequency Division Duplex (FDD), uses two different sets of frequencies for its downlink and uplink; the other, Time Division Duplex (TDD), uses just one set for both downlink and uplink.
Physical downlink control channel.
Besides the main-channel which includes uplink, downlink, and interference link, there also exists an out-of-band wireless side channel between the uplink mobile and downlink mobile.
MAC signaling concerns both allocations of CH-SACH in the current frame and MR-SACH in the next frame (uplink, downlink and direct link map of PHY resources).
Otherwise, the link (downlink or uplink) that finishes its data transmission earlier will be idle for the remainder of the time of that round.
It is based on the observed signal-to-interference-plus-noise ratio (SINR) and used by the HeNB for downlink scheduling and link adaptation [28].
This can be accomplished by channel estimation on the opposite link (downlink) in time-division duplex systems or by communication of explicit side information within the coherence time of the channel.
