Capacity Evaluation of DF Protocols for OFDMA Infrastructure Relay Links

Riihonen, Taneli; Wichman, Risto; Werner, Stefan

doi:10.1109/glocom.2009.5425686

Cited by 4 publications

(6 citation statements)

References 12 publications

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“…where R DF .Â, / is defined in (10). Note that when R DF .Â, / is maximized, P .1/ n .Â, / and P .2/ n .Â, / must satisfy the following equation:…”

Section: Resource Allocation Schemes For Ofdm Relay Systemsmentioning

confidence: 99%

“…In literature, the resource allocation for such systems has been studied extensively, such as [8][9][10][11] for DF protocols and [12][13][14] for AF protocols, but they just concentrated on maximizing the system capacity without any QoS requirement. In literature, the resource allocation for such systems has been studied extensively, such as [8][9][10][11] for DF protocols and [12][13][14] for AF protocols, but they just concentrated on maximizing the system capacity without any QoS requirement.…”

Section: Introductionmentioning

confidence: 99%

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Resource allocation for OFDM relay systems with statistical QoS guarantees

Huang

Zhang

et al. 2012

Int J Communication

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By integrating the concept of effective capacity, we propose the resource allocation schemes for subcarrierpair based OFDM decode-and-forward and amplify-and-forward relay systems for quality-of-service (QoS) guarantees. The objective is to maximize the system throughput subject to a given statistical delay QoS constraint. First, we pair the subcarriers over the source-relay channel and the relay-destination channel by the descending order of the subcarriers' channel gains. Second, by making use of the derived equivalent endto-end channel gains of the subcarrier pairs, we apply joint water-filling power allocation over the subcarrier pairs and then partition the power of the subcarrier pairs between the source and the relay. We prove that as the equivalent end-to-end channel gains of the subcarrier pairs are given, the combination of sorted subcarrier pairing and joint water-filling power allocation is jointly optimal to maximize the effective capacity. The simulation results show that our proposed schemes achieve the highest effective capacity for OFDM decodeand-forward and amplify-and-forward relay systems as compared with other existing schemes. The results also verify that our proposed schemes can efficiently provide different levels of delay QoS guarantees, even if under the stringent delay QoS constraints.

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“…where R DF .Â, / is defined in (10). Note that when R DF .Â, / is maximized, P .1/ n .Â, / and P .2/ n .Â, / must satisfy the following equation:…”

Section: Resource Allocation Schemes For Ofdm Relay Systemsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Resource allocation for OFDM relay systems with statistical QoS guarantees

Huang

Zhang

et al. 2012

Int J Communication

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“…The presence of a finite buffer can also show how it can be used as an indicator of the access link quality: the higher the emptying speed of the buffer, the higher the rate DeNB RN UE UE 978-1-4244-8327-3/11/$26.00 ©2011 Crown achievable between the RN and the UE. Our approach is complementary to that one proposed in [13], where authors investigate the performance of RNs with infinite buffer sizes. In this paper we study the relayed user throughput and the overflow/underflow probabilities in the case of finite buffer at the RN, and compare our results to the scenario without buffer at the RN.…”

Section: Introductionmentioning

confidence: 99%

On Buffering at the Relay Node in LTE-Advanced

Vitiello

Riihonen

Hämäläinen

et al. 2011

2011 IEEE Vehicular Technology Conference (VTC Fall)

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In this paper, we study the performance of a LTE-A relay-aided system with limited buffer size at the relay node. In presence of a link quality mismatch between the backhaul and access links of the relay node, we analyze the impact of the buffer size on the occurrence of undesirable events such as buffer overflows or underflows. Based on simulations, we find out that the size of the buffer at the RN can positively influence the throughput performance of the served users. Finally, we observe that in different relaying conditions, the buffer size setting plays an important role on the overall system performance, especially in terms of underflow and overflow occurrence.

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“…Specifically, for AF OFDM(A) relay systems, power allocation and subcarrier pairing (SP) schemes have been studied in [8] and [9]- [12], respectively, and have been jointly exploited in [13] and [14]. These power allocation and SP schemes have also been studied for DF OFDM relay systems in [15], [16] and [11], [17], respectively, and a scheme that utilizes joint coding across subcarriers has also been developed in [18] as an alternative for SP. To fully exploit the available degrees of freedom in cooperative OFDM systems, knowledge of the channel state information is often needed at the receiver and/or transmitter.…”

mentioning

confidence: 99%

“…In addition to the results in [33] and [34], this paper provides results based on more general channel models, detailed derivations of the feedback gain for cases with and without SP, and full technical proofs of the propositions and lemmas. Note that the proposed IterPR scheme can also be applied to DF systems, e.g., [11], [15]- [17], or, in particular, to joint coding systems, e.g., [18]. However, a more suitable criterion, such as the system capacity or the outage probability, should be adopted in place of the minimum effective SNR in this case.…”

mentioning

confidence: 99%

Feedback-Aided Pilot Placement and Subcarrier Pairing for AF OFDM Relay Channels

Sung

Hong

Chao

2013

IEEE Trans. Veh. Technol.

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Abstract-This paper examines the use of channel feedback to adaptively determine pilot placement among subcarriers in amplify-and-forward (AF) orthogonal frequency-division multiplexing (OFDM) relay systems. With feedback of the previous channel estimate, pilot subcarriers at the source and relay can be reassigned to reduce channel estimation error and ensure that good subcarriers are made available for data transmission. The minimum effective signal-to-noise ratio (SNR) among data subcarriers is utilized as the performance metric for the optimization of the pilot locations. The effective SNR is defined as the receive SNR at the destination, taking into consideration the source-to-relay (SR) and relay-to-destination (RD) channels, as well as their respective channel estimation errors. The feedback gain, which is defined as the ratio between the minimum effective SNR achieved with the optimal feedback-aided pilot placement and that achieved with the equal-spaced pilot placement, is used to measure the gains achieved through feedback. In this paper, we first derive an analytic lower bound on the optimal feedback gain and show its rate of increase with respect to the number of subcarriers. These studies are performed for systems both without and with subcarrier pairing (SP) at the relay. Specifically, in systems without SP, the relay forwards each datum on the same subcarrier on which it is received. In systems with SP, the relay is allowed to reassign the subcarriers used to forward the data received from the source. With the goal of maximizing the minimum effective SNR, the optimal SP scheme is shown to be an inverse mapping between the SR and RD subcarriers with respect to their channel gains. Due to the complexity of finding the optimal placement, a suboptimal but efficient algorithm called the iterative pilot relocation (IterPR) scheme is then proposed. The effectiveness of the proposed IterPR schemes is demonstrated through numerical simulations.Index Terms-Channel estimation, feedback, orthogonal frequency-division multiplexing (OFDM), pilot placement, relaying, subcarrier pairing (SP).

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Capacity Evaluation of DF Protocols for OFDMA Infrastructure Relay Links

Cited by 4 publications

References 12 publications

Resource allocation for OFDM relay systems with statistical QoS guarantees

Resource allocation for OFDM relay systems with statistical QoS guarantees

On Buffering at the Relay Node in LTE-Advanced

Feedback-Aided Pilot Placement and Subcarrier Pairing for AF OFDM Relay Channels

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