LTE In-Band Relay Prototype and Field Measurement

Relaying is a feature defined in LTE Release 10 to provide coverage in new areas and/or to improve cell-edge throughput. For the purpose of investigating relay´s performance in a real network, an LTE TDD in-band relay prototype was developed. Based on this prototype some field measurements were conducted using LTE Release-8 terminals. Both indoor scenarios and outdoor scenarios were tested. Measurement results show that relays (once properly deployed) provide good coverage in the coverage holes of a donor eNB. Besides coverage extension, relays can also improve data rate in the poorly-covered area of a donor eNB, i.e. cell edge. The throughput of a terminal served by this relay prototype reaches around 8 Mbps in the uplink and 20 Mbps in the downlink. Regarding latency, given uplink data is always scheduled, the measured round-trip time via the relay is around 10 ms larger than that directly via the donor eNB.