System-Level Study of Data Duplication Enhancements for 5G Downlink URLLC

Centenaro, Marco; Laselva, Daniela; Steiner, Jens; Pedersen, Klaus I.; Mogensen, Preben

doi:10.1109/access.2019.2961658

Cited by 28 publications

(12 citation statements)

References 24 publications

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“…On the other hand, to face the latency issue, we assume a reduced HARQ RTT [37]- [39] as well as a consecutive TTI assignment using multiple HARQ processes so that the relay has to wait just 2 TTIs to receive the ACK/NACK instead of 4 TTIs for LTE systems.…”

Section: Relay-based Harq Proceduresmentioning

confidence: 99%

HARQ in Full-Duplex Relay-Assisted Transmissions for URLLC

Airod

Chafnaji

Yanıkömeroğlu

2021

IEEE Open J. Commun. Soc.

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The Release 16 completion unlocks the road to an exciting phase pertain to the sixth generation (6G) era. Meanwhile, to sustain far-reaching applications with unprecedented challenges in terms of latency and reliability, much interest is already getting intensified toward physical layer specifications of 6G. In support of this vision, this work exhibits the forward-looking perception of full-duplex (FD) cooperative relaying in support of upcoming generations and adopts as a mean concern the critical contribution of hybrid automatic repeat request (HARQ) mechanism to ultra-reliable and low-latency communication (URLLC). Indeed, the HARQ roundtrip time (RTT) is known to include basic physical delays that may cause the HARQ abandonment for the 1 ms latency use case of URLLC. Taking up these challenges, this article proposes a hybrid FD amplify-and-forward (AF)-selective decode-and-forward (SDF) relay-based system for URLLC. Over this build system, two HARQ procedures within which the HARQ RTT is shortened, are suggested to face latency and reliability issues, namely, the proposed and the enhanced HARQ procedures. We develop then an analytical framework of this relay based HARQ system within its different procedures. Finally, using Monte-Carlo simulations, we confirm the theoretical results and compare the proposed relay-assisted HARQ procedures to the source-to-destination (S2D) HARQ-based system where no relay assists the communication between the source and the destination.

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Section: Relay-based Harq Proceduresmentioning

confidence: 99%

HARQ in Full-Duplex Relay-Assisted Transmissions for URLLC

Airod

Chafnaji

Yanıkömeroğlu

2021

IEEE Open J. Commun. Soc.

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“…In the second scenario, we consider three sub-scenarios: LTE-NR, NR-WiFi and LTE-WiFi for BLER and throughput. The second scenario compares the performances of both our schemes to that of the PDCP based duplication scheme as proposed in [33]. We first take an example of LTE assisted by WiFi.…”

Section: Combining Scenariosmentioning

confidence: 99%

“…• Scenario 2 compares the performance of the PDCP based duplication (PDCP) scheme [33] with that of the super-MAC based schemes proposed in this paper. Simulation parameters for this scenario are listed in Table 3.…”

Section: Simulationsmentioning

confidence: 99%

“…However, when all the paths (two in the simplest case) fail, then compulsory retransmission of the entire block is required. Given that the round trip time is a significant number over other fixed processing delays, the latency can increase [33]. Also, since the PDCP sits at the top of the L2 layer, the cross-layer scheme has relatively more computation complexity.…”

Section: Introductionmentioning

confidence: 99%

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Super-MAC: Data Duplication and Combining for Reliability Enhancements in Next-Generation Networks

2021

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A piece of user equipment (UE), typically, has access to multiple radio access technologies (RATS). Moreover, apart from the standard primary cellular network, the secondary cellular networks can assist the primary network in downlink UE communications. In this way, the data can reach the UE through multiple entities. This paper exploits the multiple entities' idea by proposing a cross-layer scheme that combines data to improve the block error rate (BLER) and the throughput. For this, we define a new entity, called the super-MAC, just above the Medium Access Control (MAC) layer. More specifically, we propose data duplication (at the transmitter) and combining (at UE) at the super-MAC, where the super-MAC gets the Radio Link Layer protocol data unit (RLC-PDU) and sends multiple-copies across various interfaces to different MAC-entities. In doing so, the super-MAC attaches a unique sequence number to a group of RLC-PDUs together. At the UE, the data from different MAC entities are combined at super-MAC to clear any block error. The super-MAC operates in between the Cyclic Redundancy Check and Forward Error Correction stages of the HARQ process. The additional complexity introduced by the scheme is negligible in front of the existing operations. Moreover, the average latency improves due to the significant improvement in the Block Error rate (BLER) that the combining scheme offers over the BLER of the conventional standalone system. Also, since the errors significantly reduce, the throughput shows significant improvement. Finally, the proposed scheme is an advancement in HARQ to reduce retransmissions, and hence it is suitable for the next-generation networks like B5G or 6G to adopt the super-MAC.

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“…The works in [17] and [18] study centralized radio access network (C-RAN) architecture and dynamic point selection to reduce the obstructive queuing delay of URLLC payloads. Reliability enhancement by means of data packet duplication is presented in [19], [20]. To overcome the timely handshaking procedures of grant-based scheduling in UL, the studies in [21] and [22] investigate grant free and semi-grant free access protocols, respectively.…”

Section: A Brief Overview Of the State Of The Art On Urllcmentioning

confidence: 99%

On the Multiplexing of Data and Metadata for Ultra-Reliable Low-Latency Communications in 5G

Karimi

Pedersen

Mahmood

et al. 2020

IEEE Trans. Veh. Technol.

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This paper addresses the problem of downlink radio resource management for ultra-reliable low-latency communications (URLLC) in fifth generation (5G) systems. To support low-latency communications, we study performance of two multiplexing schemes namely in-resource control signalling and joint encoding of data and metadata. In the former, the metadata and data are separately encoded and the metadata is sent at the beginning of transmission time prior to the data. Thus, it benefits from a low-complexity receiver structure to decode the data block. The latter takes advantages of transmitting a larger blocklength to enhance the reliability and improve spectrum efficiency by jointly encoding data and metadata as a single codeword. Dealing with small URLLC payloads, the overhead and error of sending metadata are not negligible and have a significant impact on the system performance in terms of resource usage the reliability of transmission. For each scheme, we derive expressions for the outage probability and resource usage by taking into account impacts of the finite blocklength payloads, overhead and error of sending metadata, and probability of error in uplink feedback channel. We propose a novel framework for joint data and metadata link adaptation to minimize the average number of allocated resources, while ensuring the stringent URLLC quality of service requirements. An optimization problem is formulated for each scheme that is mixed-integer nonconvex problem, difficult to solve in polynomial time. Solutions based on successive convex optimization are proposed. Numerical evaluations show that the proposed algorithms perform close to the optimal solution and demonstrate remarkable gains of up to 27% improvement in resource usage. Finally, we present sensitivity analysis of the results for various network parameters.

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System-Level Study of Data Duplication Enhancements for 5G Downlink URLLC

Cited by 28 publications

References 24 publications

HARQ in Full-Duplex Relay-Assisted Transmissions for URLLC

HARQ in Full-Duplex Relay-Assisted Transmissions for URLLC

Super-MAC: Data Duplication and Combining for Reliability Enhancements in Next-Generation Networks

On the Multiplexing of Data and Metadata for Ultra-Reliable Low-Latency Communications in 5G

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