Two-Way Synchronization for Coordinated Multicell Retrodirective Downlink Beamforming

Preuss, R.; Brown, Donald R.

doi:10.1109/tsp.2011.2162329

Cited by 52 publications

(25 citation statements)

References 24 publications

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“…and where f (T ) and Q are defined in (2) and (3), respectively. The remaining N − 1 slave nodes update their state estimates and predictions with K m = 0 for all m = n since they do not receive an observation.…”

Section: Delay Estimation and Filteringmentioning

confidence: 99%

“…In the context of communication networks, synchronization enables coordination among the nodes in the network and can facilitate scheduling of communication resources, interference avoidance, event detection/ordering, data fusion, and coordinated wake/sleep cycles [1]. Precise synchronization, to the order of a fraction of a carrier period, can also enable distributed transmission schemes such as retrodirective distributed beamforming [2].…”

Section: Introductionmentioning

confidence: 99%

“…Precise timestamp-free synchronization techniques accounting for propagation delays were developed recently in the context of retrodirective distributed transmit beamforming systems [2], [21]- [24]. These techniques are based on serial exchanges of unmodulated beacons through a network with a ring architecture and achieve precise synchronization through estimation of RF carrier phase and frequency offsets.…”

Section: Introductionmentioning

confidence: 99%

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Precise timestamp-free network synchronization

Brown

Klein

2013

2013 47th Annual Conference on Information Sciences and Systems (CISS)

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Abstract-This paper describes an approach to master/slave network synchronization based on bidirectional message exchanges without the use of timestamps. Rather than the usual approach of exchanging digital timestamps through a dedicated synchronization protocol, an approach is described in which synchronization information is conveyed implicitly at the physical layer through the timing of the master node's responses to the slave nodes. This approach can reduce overhead and allow the embedding of synchronization functions in existing network traffic. A timestamp-free synchronization protocol is described and its performance is quantified in the presence of delay estimation error and stochastic local oscillator dynamics. A filtering framework is also developed to allow each slave node to accurately infer and correct local clock drifts from multiple noisy clock offset estimates. Based on fundamental delay estimation bounds for narrowband signals, numerical results show that synchronization among the slave nodes can be achieved quickly and that the resulting steady-state accuracy can be sufficient to support distributed transmission techniques requiring carrier phase alignment, e.g. distributed beamforming.

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Section: Delay Estimation and Filteringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Precise timestamp-free network synchronization

Brown

Klein

2013

2013 47th Annual Conference on Information Sciences and Systems (CISS)

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“…The coarse synchronization required here can be achieved with standard techniques such as global positioning system (GPS), network time protocol (NTP), or potentially through feedback messages from the receive nodes. Precise carrier synchronization as described in [4] is not assumed, but is implicitly achieved via channel tracking and feedback. The nominal transmit frequency in the forward link from the distributed transmit cluster to the receivers is at ωc.…”

Section: System Modelmentioning

confidence: 99%

Receiver-coordinated zero-forcing distributed transmit nullforming

Brown

Bidigare

Dasgupta

et al. 2012

2012 IEEE Statistical Signal Processing Workshop (SSP)

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A coherent cooperative communication system is proposed in which a distributed array of transmit nodes forms a beam at a desired receiver while simultaneously steering nulls at several protected receivers. Coherent transmission is achieved through a receiver-coordinated protocol where the receivers in the system use state-space channel tracking and provide feedback to the transmit cluster to facilitate distributed transmission. Analytical estimates for the performance degradation in the nulls due to channel estimation errors are verified by simulations. Numerical results demonstrate that the technique is effective even with low channel measurement overhead, infrequent measurement intervals, and feedback latency.

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“…Several techniques have been proposed to enable distributed transmit beamforming including receiver coordinated one-bit feedback [1-3], receiver-coordinated explicit-feedback [4][5], master-slave synchronization with retrodirective transmission [6], round-trip [7][8], and two-way synchronization with retrodirective transmission [9][10]. Distributed transmit beamforming has also been considered for 978-1-4673-5051-8/12/$3l.00 ©20 12 IEEE 222 the downlink of cellular networks under the title "coordinated multipoint" (CoMP), e.g.…”

Section: Introductionmentioning

confidence: 99%

Implementation and demonstration of receiver-coordinated distributed transmit beamforming across an ad-hoc radio network

Bidigare

Oyarzyn

Raeman

et al. 2012

2012 Conference Record of the Forty Sixth Asilomar Conference on Signals, Systems and Computers (ASILOMAR)

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Abstract-Distributed transmit beamforming using an ad-hoc network of 10 RF transmitters was demonstrated using radio nodes developed from off-the-shelf components and modules. A time-slotted protocol allowed carrier phases from each transmitter to be measured at a receiver and fed back to the transmitters where Kalman filters were used to predict the offset phases and frequencies. Offsets were digitally compensated for during beamforming intervals. Beamforming gain within O.ldB of ideal was demonstrated across I km at 910MHz. This is the first report (to our knowledge) of a successful outdoor RF distributed transmit beamforming experiment using independent clocks at this scale.

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Two-Way Synchronization for Coordinated Multicell Retrodirective Downlink Beamforming

Cited by 52 publications

References 24 publications

Precise timestamp-free network synchronization

Precise timestamp-free network synchronization

Receiver-coordinated zero-forcing distributed transmit nullforming

Implementation and demonstration of receiver-coordinated distributed transmit beamforming across an ad-hoc radio network

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