Centralized Scheduling for Joint Decoding Cooperative Networks Subject to Signalling Delays

Diehm, Fabian; Fettweis, Gerhard

doi:10.1109/vetecf.2011.6093131

Cited by 5 publications

(5 citation statements)

References 8 publications

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“…a practical implementation as well as an extensive evaluation part is given. While the impact of backhaul delays has mainly been addressed in the context of cooperative cellular systems [27], [28], this work focuses on non-cooperative cloud-based communication systems.…”

Section: B Contribution Of This Workmentioning

confidence: 99%

Robust Rate Adaptation and Proportional Fair Scheduling With Imperfect CSI

Fritzsche

Rost²,

Fettweis

2015

IEEE Trans. Wireless Commun.

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In wireless fading channels, multi-user scheduling has the potential to boost the spectral efficiency by exploiting diversity gains. In this regard, proportional fair (PF) scheduling provides a solution for increasing the users' quality of experience by finding a balance between system throughput maximization and user fairness. For this purpose, precise instantaneous channel state information (CSI) needs to be available at the transmitter side to perform rate adaptation and scheduling. However, in practical setups, CSI is impaired by, e.g., channel estimation errors, quantization and feedback delays. Especially in centralized cloud based communication systems, where main parts of the lower layer processing is shifted to a central entity, high backhaul latency can cause substantial CSI imperfections, resulting in significant performance degradations. In this work robust rate adaptation as well as robust PF scheduling are presented, which account for CSI impairments. The proposed rate adaptation solution guarantees a fixed target outage probability, which is of interest for delay critical and data intensive applications, such as, video conference systems. In addition to CSI imperfections the proposed scheduler is able to account for delayed decoding acknowledgements from the receiver.

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Section: B Contribution Of This Workmentioning

confidence: 99%

Robust Rate Adaptation and Proportional Fair Scheduling With Imperfect CSI

Fritzsche

Rost²,

Fettweis

2015

IEEE Trans. Wireless Commun.

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“…Another approach is to use a greedy algorithm as in, e.g. [34][35][36] that assigns one user at a time to a given resource, forming a near-optimal solution both in terms of spatially compatible users and exploiting multiuser diversity. This, however, requires repeated pre-evaluation of beamformers, resulting in a high complexity.…”

Section: Assumptions Design Choices and Related Workmentioning

confidence: 99%

Design and measurement-based evaluations of coherent JT CoMP: a study of precoding, user grouping and resource allocation using predicted CSI

Apelfröjd

Sternad

2014

J Wireless Com Network

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Coordinated multipoint (CoMP) transmission provides high theoretic gains in spectral efficiency with coherent joint transmission (JT) to multiple users. However, this requires accurate channel state information at the transmitter (CSIT) and also user groups with spatially compatible users. The aim of this paper is to use measured channels to investigate if significant CoMP gains can still be obtained with channel estimation errors. This turns out to be the case, but requires the combination of several techniques. We here focus on coherent downlink JT CoMP to multiple users within a cluster of cooperating base stations. The use of Kalman predictors is investigated to estimate the complex channel gains at the moment of transmission. It is shown that this can provide sufficient CSIT quality for JT CoMP even for long (>20 ms) system delays at 2.66 GHz at pedestrian velocities or, for lower delays, at 500 MHz, at vehicular velocities. A user grouping and resource allocation scheme that provides appropriate groups for CoMP is also suggested. It provides performance close to that obtained by exhaustive search at very low complexity, low feedback cost and very low backhaul cost. Finally, a robust linear precoder that takes channel uncertainties into account when designing the precoding matrix is considered. We show that, in challenging scenarios, this provides large gains compared with zero-forcing precoding. Evaluations of these design elements are based on measured channels with realistic noise and intercluster interference assumptions. These show that high JT CoMP gains can be expected, on average over large sets of user positions, when the above techniques are combined -especially in severely intracluster interference limited scenarios.

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“…Forω = ω * , ω = ω * , and independent observations of the corresponding objective values, if 19) the sequence {ω (t) } is a homogeneous irreducible and aperiodic Markov chain with state space Ω, and the sequence {ω (t) } converges almost surely to ω * .…”

Section: Convergence Discussionmentioning

confidence: 99%

“…and Fettweis study the decoding strategies for uplink CoMP under a constrained backhaul and imperfect CSI [17]. The effect of signalling delay on the performance of centralized scheduling is investigated in [18] and [19]. The system considered is a joint detection cooperating system.…”

Section: Coordinated Multi-point Cellular Networkmentioning

confidence: 99%

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Stochastic Optimization for Emerging Wireless Networking Paradigms with Imperfect Network State Information

Cai¹

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In wireless networks, network state information (NSI) usually consists of channel state information (CSI) and queuing state information (QSI). NSI, especially CSI, has been widely used in designs and configurations of wireless networks. However, most of the existing works assume that NSI is perfectly available at the decision making entities in the network. In general such assumption is not practical because First of all, I would like to gratefully thank my supervisor, Prof. F. Richard Yu, for his invaluable support and wonderful supervision. His technical insight and ongoing encouragement have been a constant source of motivation. The innumerable discussions with him and his ideas on the research projects have been the most dispensable input for my research. His comments and suggestions on my works not only increase the quality of the research but also provide a source of thought for my career.

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Centralized Scheduling for Joint Decoding Cooperative Networks Subject to Signalling Delays

Cited by 5 publications

References 8 publications

Robust Rate Adaptation and Proportional Fair Scheduling With Imperfect CSI

Robust Rate Adaptation and Proportional Fair Scheduling With Imperfect CSI

Design and measurement-based evaluations of coherent JT CoMP: a study of precoding, user grouping and resource allocation using predicted CSI

Stochastic Optimization for Emerging Wireless Networking Paradigms with Imperfect Network State Information

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