An Analysis of Uplink Base Station Cooperation with Practical Constraints

Balachandran, K.; Kang, Joseph H.; Karakayali, Kemal; Rege, Kiran M.

doi:10.1109/twc.2012.011812.110279

Cited by 6 publications

(9 citation statements)

References 13 publications

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“…Therefore, (13) and (15b) can be rewritten as (17) and (18), respectively, which means that S1 with N s = (N − 1) and the optimal MRC scheme have the same soft output of the demapper for the first bit of the symbol x.…”

Section: Qpsk Modulationmentioning

confidence: 99%

Selective cooperative decoding based on a hard‐decision‐aided log‐likelihood ratio approximation

Baek

Lee

2015

IET Communications

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This study presents novel strategies to improve the decoding performance through base-station cooperation. In the proposed schemes, the soft output of the demapper at a serving base station (SBS) is replaced by a combination of log-likelihood ratio information, which is generated through demodulation by neighbouring base stations (NBSs) as well as the SBS. For the information used in the cooperation, soft information is first considered. Combining the soft information transmitted from all NBSs provides close-to-optimal performance, but it still requires a high amount of overhead to be passed over the backhaul links. In the proposed schemes, the SBS only cooperates with the reliable NBSs, which are identified on the basis of the magnitude of the metrics transmitted from the NBSs, to achieve a tradeoff between performance and overhead. In addition, the use of hard information instead of soft information is also proposed to further reduce the backhaul overhead. In this scheme, the metric values as well as the hard information are exploited to generate the updated soft information for the channel decoder. In the simulation results, it is shown that the proposed schemes provide better error performance compared with the conventional schemes under limited backhaul capacities.

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Section: Qpsk Modulationmentioning

confidence: 99%

Selective cooperative decoding based on a hard‐decision‐aided log‐likelihood ratio approximation

Baek

Lee

2015

IET Communications

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“…NICE has been shown to significantly improve the achievable rates through interference cancellation [3] [4]. With cancellation of up to six dominant interferers and three rounds of NICE decoding, edge and mean user throughputs were approximately doubled, achieving similar throughput gains as network MIMO but with significantly less backhaul.…”

Section: System Modelmentioning

confidence: 99%

“…Another uplink cooperative scheme is the Network Interference Cancellation Engine (NICE) [3] [4]. By opportunistically sharing decoded bits between base stations, NICE has been shown to yield similar throughput gains as network MIMO but with one to two orders of magnitude less backhaul.…”

Section: Introductionmentioning

confidence: 99%

Base Station Cooperation with Non-Ideal Backhaul and Non-Full Buffer Traffic

Balachandran¹,

Kang²,

Karakayali³

et al. 2014

2014 IEEE 80th Vehicular Technology Conference (VTC2014-Fall)

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Base station cooperation has been shown to significantly mitigate the interference perceived in cellular networks and improve the quality of user experience. On the uplink, joint processing (JP) across antennas within a cluster of base stations yields significant gain, but requires significant backhaul to transport complex I & Q signals. The Network Interference Cancellation Engine (NICE) can yield throughput gains similar to that of JP, but with one to two orders of magnitude less backhaul. While NICE demonstrates significant potential for cellular networks, its performance has been evaluated under somewhat idealistic conditions. For instance, full buffer traffic has generally been assumed, thereby leading to a fully loaded system with strong interference. Bursty traffic may result in a partially loaded system with less interference and impact the gains of interference-mitigating techniques such as NICE. In addition, an ideal backhaul with negligible delay has generally been assumed. However, delays in information exchanges between base stations may decrease the efficacy of base station cooperation. In this paper, the performance of NICE is evaluated under non full buffer traffic and non-ideal backhaul.

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“…Motivated by the need to achieve performance improvements similar to network MIMO but with much lower backhaul overhead, we have proposed a novel network interference cancellation engine (NICE) technique which opportunistically cancels dominant out‐of‐cell interferers by exchanging decoded data for these interferers among cooperating cells [3, 4]. Base stations attempting to decode a user can then generate estimates of the signals received from the interfering mobile station and cancel them out from their respective aggregate received signals, thus improving the desired user's signal‐to‐interference‐plus‐noise ratio (SINR) and, consequently, the transmission rate at which the user can be decoded.…”

Section: Network‐centric Uplink Cooperation Techniques For Interferenmentioning

confidence: 99%

“…The inter‐site distance is assumed to be 500 meters, which is representative of an interference‐limited deployment. We also assume a mobile terminal with a single transmit antenna and two uncorrelated receive antennas at each sector; ideal channel estimation is assumed for all the techniques considered (see [4] for results with non‐ideal LMMSE‐based channel estimation). HARQ with incremental redundancy is employed with a maximum of four transmissions and a block error rate target of 20 percent on the first transmission.…”

Section: Performance Benefits Of Uplink Cooperation Schemesmentioning

confidence: 99%

Network-centric cooperation schemes for uplink interference management in cellular networks

Balachandran

Kang²,

Karakayali³

et al. 2013

Bell Labs Tech. J.

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The huge growth in demand for wireless data, combined with shortages of spectrum, has led to an urgent need for spectral effi ciency and cell-edge performance improvements in cellular networks. Macrocells are shrinking in size, and heterogeneous networks are being deployed where small cells and macrocells now share the same spectrum. With these trends in cellular network evolution, out-of-sector interference is becoming a major impediment. Impairments due to interference are especially severe on the uplink, where near-far effects are more likely to be experienced. This paper provides a holistic view of the network-centric cooperation schemes that have emerged as strong candidates for uplink interference management in evolving cellular networks (e.g., networks based on 3GPP Long Term Evolution based air-interface technologies and beyond). In particular, we introduce three novel approaches: 1) network multiple input multiple output (MIMO), which carries out joint multi-antenna signal processing across sectors; 2) network interference cancellation engine (NICE) which opportunistically cancels dominant interferers that have already been decoded at neighboring sectors and decreases backhaul overhead by one to two orders of magnitude; and 3) a hybrid approach which combines the strengths of both network MIMO and NICE in an attempt to achieve further spectral effi ciency without incurring huge backhaul overhead. Several considerations of both theoretical and practical signifi cance (overhead, latency) related to these approaches are discussed, and simpler variants that may apply in the context of heterogeneous networks are also considered. Quantitative investigations of these network-centric cooperation schemes in realistic operating environments show that substantial improvement may be achieved in average and cell-edge spectral effi ciency.

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An Analysis of Uplink Base Station Cooperation with Practical Constraints

Cited by 6 publications

References 13 publications

Selective cooperative decoding based on a hard‐decision‐aided log‐likelihood ratio approximation

Selective cooperative decoding based on a hard‐decision‐aided log‐likelihood ratio approximation

Base Station Cooperation with Non-Ideal Backhaul and Non-Full Buffer Traffic

Network-centric cooperation schemes for uplink interference management in cellular networks

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