Rake fingers versus multiple antennas for UWB relay systems - which one is better?

Ultra Wideband Systems with MIMO

“…Up to now, freedoms F1, F3, F4 and F6 were partly examined in [9,[147][148][149][150], and freedom F5 was mentioned in [45,46]. Freedom F2 remains unexplored, and there are many options for freedom F3.…”

“…Note that each node considered in [9] is equipped with only a single antenna, while the 'space' refers to the multiple antennas across multiple nodes, including both the source and relay nodes. In [147,149], a multi-antenna relaying scheme is proposed, where multiple antennas are mounted at the relay node to increase the reliability of the relay by making use of the spatial diversity of the channels. Note that, in [149], the multiple antennas are used for the purposes of both reception and transmission at the relay node, and the gain thus obtained will be doubled compared with the cases in which these antennas are deployed either at the source node or at the destination node.…”

“…Note that, in [149], the multiple antennas are used for the purposes of both reception and transmission at the relay node, and the gain thus obtained will be doubled compared with the cases in which these antennas are deployed either at the source node or at the destination node. Since UWB systems typically use Rake receivers to collect the energy spread over multipaths and the number of Rake fingers is an important factor which affects the complexity/cost of UWB systems, the compromise between the number of antennas at the relay node and the number of Rake fingers was investigated in [147,148]. The results show that generally increasing the number of antennas at the relay node yields better BER performance than increasing the number of Rake fingers for a fixed product of the two numbers.…”

“…The results show that generally increasing the number of antennas at the relay node yields better BER performance than increasing the number of Rake fingers for a fixed product of the two numbers. In [150], the results of [147,148] are extended to the case where multiple antennas are also equipped at the source and destination nodes. In [148], a differential coded transmitted-reference (DCTR) relay system is proposed, by which the traditional synchronizer and Rake receiver can be removed.…”

Performance Investigation of a UWB Relay System using Multiple Relays with Multiple Antennas in IEEE 802.15.3a Channel

“…In our previous work [12], a two-hop detect-and-forward relay system, in which the relay and receiver use a practical coherent UWB detection, i.e., selective-Rake reception [10], has been presented. In this system, a two-antenna relay has also been proposed to exploit spatial diversity, resulting in improved BER performance.…”