2 research outputs found
Impact of Relay Cooperation on the Performance of Large-scale Multipair Two-way Relay Networks
We consider a multipair two-way relay communication network, where pairs of
user devices exchange information via a relay system. The communication between
users employs time division duplex, with all users transmitting simultaneously
to relays in one time slot and relays sending the processed information to all
users in the next time slot. The relay system consists of a large number of
single antenna units that can form groups. Within each group, relays exchange
channel state information (CSI), signals received in the uplink and signals
intended for downlink transmission. On the other hand, per-group CSI and
uplink/downlink signals (data) are not exchanged between groups, which perform
the data processing completely independently. Assuming that the groups perform
zero-forcing in both uplink and downlink, we derive a lower bound for the
ergodic sumrate of the described system as a function of the relay group size.
By close observation of this lower bound, it is concluded that the sumrate is
essentially independent of group size when the group size is much larger than
the number of user pairs. This indicates that a very large group of cooperating
relays can be substituted by a number of smaller groups, without incurring any
significant performance reduction. Moreover, this result implies that relay
cooperation is more efficient (in terms of resources spent on cooperation) when
several smaller relay groups are used in contrast to a single, large group.Comment: Accepted to Globecom 2018. Copyright 2018 IEE
Impact of Relay Cooperation on the Performance of Large-Scale Multipair Two-Way Relay Networks
We consider a multipair two-way relay communication network, where pairs of user devices exchange information via a relay system. The communication between users employs time division duplex, with all users transmitting simultaneously to relays in one time slot and relays sending the processed information to all users in the next time slot. The relay system consists of a large number of single antenna units that can form groups. Within each group, relays exchange channel state information (CSI), signals received in the uplink and signals intended for downlink transmission. On the other hand, per-group CSI and uplinkdownlink signals (data) are not exchanged between groups, which perform the data processing completely independently. Assuming that the groups perform zero-forcing in both uplink and downlink, we derive a lower bound for the ergodic sumrate of the described system as a function of the relay group size. By close observation of this lower bound, it is concluded that the sumrate is essentially independent of group size when the group size is much larger than the number of user pairs. This indicates that a very large group of cooperating relays can be substituted by a number of smaller groups, without incurring any significant performance reduction. Moreover, this result implies that relay cooperation is more efficient (in terms of resources spent on cooperation) when several smaller relay groups are used in contrast to a single, large group