1 Introduction
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How to split the radio resources at DeNB for serving the direct and the backhaul link?
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How to ensure that Quality of Service (QoS) constraints of all users, including those served over multiple hops, are appropriately satisfied?
1.1 Resource partitioning in REN
1.2 QoS provisioning in REN
1.3 Our contribution
2 System overview
2.1 Relays in LTE-Advanced
QoS provisioning in LTE-Advanced
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the delay budget, DProfile(n): the maximum acceptable packet delay;
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the maximum block error rate;
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the service priority index, P(n): a scalar ranging from one to nine; the higher the index, the lower is the service priority;
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some real-time QCIs also specify a Guaranteed bit-rate (GBR), GBR(n), the specification of GBR value for a particular service is left open for the service provider.
3 Proposed resource allocation strategy
3.1 Explicit resource partitioning at DeNB between access and backhaul links
3.2 QoS-aware resource allocation
3.2.1 Addressing QoS support in relay-enhanced scenarios
3.2.2 Proposed scheduling metric
3.2.3 Two-stage scheduler
4 Simulation setup
4.1 Macro cell configuration
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Duplexing: FDD
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Carrier frequency: 2 GHz
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TTI duration: 1 ms
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Speed: 3 km/h
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Penetration loss: 20 dB
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Path loss: Only NLOS term used
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3-D antenna pattern with 15 degree electrical downtilt
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DeNB antenna height: 32 m
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UE antenna height: 1.5 m
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Minimum distance between DeNB and UE: 35 m
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DeNB Tx power: 43 dBm
4.2 Relay configuration
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Carrier frequency, duplexing, TTI duration, speed, and penetration loss: same as for macro cell
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Path loss: Only NLOS term (for relay to UE) used
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2-D omni-directional antenna pattern with 5 dBi gain, 2Tx and 2Rx antenna ports
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RN antenna height: 5 m
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UE antenna height: same as for macro cell
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Minimum distance between RN and UE: 10 m
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RN Tx power: 30 dBm
4.3 Traffic model
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Voice over IP (VoIP) traffic is emulated using a constant bit-rate (CBR) traffic generator working at 128 kbps. The QCI for this type of traffic is defined as QCI-1[24]: The packets are allowed to have a maximum end-to-end delay of 100 ms, and the service priority is defined as 2.
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Video streaming services. In our evaluations we configure a CBR of 256 kbps due to the limitations of the mobile devices, such as processing capabilities. The QCI for this type of traffic is defined as QCI-4[24]: The maximum packet end-to-end delay is 300 ms, and the service priority is 5.
5 Simulation results
5.1 Explicit resource partitioning at DeNB
5.2 Implicit resource partitioning and QoS provisioning
UE type | Fraction of satisfied users w.r.t. | |||
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Achieved throughput | Experienced delay | |||
Conv. (%) | Prop. (%) | Conv. (%) | Prop. (%) | |
Video M-UEs | 8.1 | 88.8 | 74.7 | 95.3 |
VoIP M-UEs | 80.0 | 99.4 | 90.5 | 99.0 |
Video R-UEs | 100.0 | 100.0 | 100.0 | 100.0 |
VoIP R-UEs | 100.0 | 100.0 | 100.0 | 100.0 |