Furthermore, if frequency hopping is performed, the number of adjacent pilots transmitted in the same subband is two for inter-subframe frequency hopping and only one for intra-subframe frequency hopping where frequency hopping is performed on a per-slot basis.
During coordination among cells in CoMP set for joint relay link transmissions in each backhaul subframe, orthogonal frequency resource allocation is applied among the set of served RNs.
In practice, downlink backhaul radio resources are achieved by allocating RNs up to six multicast-broadcast single frequency network (MBSFN) subframes (frame numbers 0, 1, 2, 3, 6, 7, 8) out of the ten subframes (each of 1 ms duration) specified in the 3GPP Release 8 LTE frame structure [42].
Consequently, the subframe can be defined by physical frequency and time indices.
For example, almost blank subframe (ABS) is a time orthogonal interference coordination scheme; fractional frequency reuse (FFR) is a frequency orthogonal interference coordination scheme; coordinated beamforming (CB) is a spatial orthogonal interference coordination scheme [4 7].
Accompanied by the re-distribution, the radio resource blocks in the frequency domain are allocated jointly per subframe.
The access is frame based, where each radio frame is subdivided into subframes in time domain and into subbands in frequency domain.
Table 1 Simulation parameters Parameter Value Cellular layout Hexagonal grid, Three sectors per cell, reuse 1 Carrier frequency 2 GHz System bandwidth 10 MHz Subframe duration 1 ms Number of RBs 50 Number of macrocells 1 Number of PBSs per macrocell P {1,2,3} Max.
Figure 6 Transmit power reconfiguration frequency comparison of different strategies in 200 subframes.
In the case of FDD, because the downlink and uplink transmissions are separated in the frequency domain, there is no allocation of subframes in time.
Fast fading (time and frequency selective) was then generated for each UE to determine the instantaneous (per subframe) SINR.
