Achieving the Degrees of Freedom of Wireless Multi-User Relay Networks

Wang, Chao; Farhadi, Hamed; Skoglund, Mikael

doi:10.1109/tcomm.2012.062512.100580

Cited by 21 publications

(20 citation statements)

References 25 publications

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“…2, it can be observed that applying the CSR scheme with the proposed interference alignment design strictly outperforms that with the designing approach shown in [22]. Although the AND scheme can attain the highest DoF performance when the number of relays is small, its achievable sum DoF, d A1 , cannot be higher than half value of the performance limit does not apply to the proposed CSR scheme.…”

Section: Theorem 1 In a Time-varying (Or Frequency-selective) Fadingmentioning

confidence: 90%

“…In our previous work [22] we investigated communications in a two-hop network with one layer of half-duplex relays being deployed to establish information delivery links between several dedicated source-destination pairs. Through combining the concepts of successive relaying [23] and interference alignment, we proposed a cluster successive relaying transmission scheme, which divides the half-duplex relays into two clusters and alternatively activates them to emulate full-duplex operation, to efficiently use the available radio resources.…”

Section: A Backgroundmentioning

confidence: 99%

“…Since the system model becomes much more complex, we present a more careful transmission and associated interference alignment design to tackle interference issues. The network structure contains that considered in [22] as a special case. In two-hop systems, although the interference alignment design proposed in [22] can still be applicable, we show that the sum DoF performance attained in this paper outperforms that reached by [22] in many network topologies.…”

Section: B Contributionsmentioning

confidence: 99%

“…Note that the idea of dividing the relays into two alternatively activated clusters was first proposed in our earlier work [22]. The application scenario was limited to a twohop network with m dedicated source-destination pairs and k intermediate relays.…”

Section: Theorem 1 In a Time-varying (Or Frequency-selective) Fadingmentioning

confidence: 99%

“…Define a T × T matrixṼ [n] q as expressed by (22) at the top of the next page, whereV { |S n |B n c Γ +C n (c + 1) Γ } ≥ B n |S n |c Γ +C n (c + 1) Γ .) For any n, from the construction process described in (20) and (21), it is not difficult to see that for any row ofṼ [n] q , all the monomial entries are unique.…”

Section: ) Decodingmentioning

confidence: 99%

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Multi-User Multi-Hop Relay Networks: Transmission Schemes and Degrees of Freedom

Wang

Skoglund

2015

IEEE Trans. Wireless Commun.

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We study the achievable sum degrees of freedom (DoF) in wireless single-antenna multi-user multi-hop relay networks. In most existing works targeting on this problem, it is assumed that relays operate in perfect full-duplex fashion and can also shield their receptions from the transmissions of other relays in the same and rear layers. In practice, such ideal assumptions are normally hard to realize. And a naive adoption of halfduplex operation in relays may result in significantly inefficient use of available radio resources. We propose spectrally-efficient transmission schemes to address this issue. A lower-bound to the networks' available DoF (i.e., optimally achievable sum DoF) hence can be attained. Our results indicate that besides providing information delivery paths, relays can also bring DoF gain over single-hop networks, even when relay interference issues are taken into consideration. This lower-bound would approach the upper-bound of the available DoF, if each relay layer deploys more nodes. When the number of relays in every layer is infinitely large, the exact available DoF is identified, which shows that handling interference issues through distributed signal processing and half-duplex operation across multiple layers of terminals may not negatively affect DoF performance, compared with ideal fullduplex and multi-antenna networks.Index Terms-Degrees of freedom (DoF), multi-user multihop relay networks, spectrally-efficient half-duplex relaying, interference alignment

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Section: Theorem 1 In a Time-varying (Or Frequency-selective) Fadingmentioning

confidence: 90%

Section: A Backgroundmentioning

confidence: 99%

Section: B Contributionsmentioning

confidence: 99%

Section: Theorem 1 In a Time-varying (Or Frequency-selective) Fadingmentioning

confidence: 99%

Section: ) Decodingmentioning

confidence: 99%

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Multi-User Multi-Hop Relay Networks: Transmission Schemes and Degrees of Freedom

Wang

Skoglund

2015

IEEE Trans. Wireless Commun.

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Successive relaying for large MIMO amplify‐and‐forward relay networks

Hong

2018

Int J Communication

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In this paper, we consider a large relay network with one source, K relays and M users, where the source and relays are equipped with W and N antennas, respectively. We propose an amplify-and-forward successive relaying protocol in which the relays are divided into 2 groups to successively help transmission to M users. Achievable sum rate of the proposed protocol is derived and found to scale as M log (K) + (1) when N and M are fixed and K → ∞ . On the other hand, when M and K are fixed and N → ∞, the achievable sum rate scales as M log (N) + (1). Therefore, the scaling law of the achievable sum rate coincides with the capacity scaling law of the considered network. Then, both precoding at the source and grouping of the relay nodes are jointly optimized to further improve the proposed protocol. Numerical results show that the proposed successive relaying protocol can outperform the conventional 2-slot relaying protocol and the proposed joint optimization scheme for source precoding and relay grouping bring considerable rate gain. KEYWORDS successive relaying, MIMO, precoding, relay grouping Int J Commun Syst. 2018;31:e3545.wileyonlinelibrary.com/journal/dac

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Neutralizing interferences in two‐hop amplify‐and‐forward MIMO relay systems

Shin

Noh

2016

IEEJ Transactions Elec Engng

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In this paper, we present the interference neutralization technique for two-hop multiple-input multiple-output (MIMO) relay systems. It enables multiple MIMO transmitters (sources) to simultaneously transmit independent data streams to their MIMO receivers (destinations) without mutual interferences, thereby improving spectral efficiency of the systems. To neutralize the mutual interferences using multiple amplify-and-forward (AF) MIMO relays, we establish the sufficient condition for the antenna configuration in the MIMO relay networks, and provide a filter design technique for the AF MIMO relays. The proposed method increases sum rates of the systems linearly with the number of transmitters participating in simultaneous transmission. To improve the sum rates further, this method is combined with transmit power allocation using the water-filling algorithm. In addition, it is shown that by employing the minimum number of relays required to meet the sufficient condition, the system cost for the proposed method can be reduced without compromising the sum rate performance severely. Finally, simulation results successfully demonstrate that by exploiting radio resources such as frequency and time efficiently, the proposed method achieves a higher sum rate than the existing techniques based on interference avoidance.

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Achieving the Degrees of Freedom of Wireless Multi-User Relay Networks

Cited by 21 publications

References 25 publications

Multi-User Multi-Hop Relay Networks: Transmission Schemes and Degrees of Freedom

Multi-User Multi-Hop Relay Networks: Transmission Schemes and Degrees of Freedom

Successive relaying for large MIMO amplify‐and‐forward relay networks

Neutralizing interferences in two‐hop amplify‐and‐forward MIMO relay systems

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