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SparkLink: A short-range wireless communication protocol with ultra-low latency and ultra-high reliability

March 2023
The Innovation 4(2):100386

DOI:10.1016/j.xinn.2023.100386

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Typical applications of SparkLink in different scenarios, including smart cars, intelligent manufacturing, smart terminals, and smart homes

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SparkLink: A short-range wireless communication protocol

with ultra-low latency and ultra-high reliability

Mingjin Gao,

1,2,

*Lei Wan,

Rujing Shen,

1,2,

*Yongqiang Gao,

Jian Wang,

Yonghui Li,

and Branka Vucetic

State Key Lab of Processors, Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100190, China

University of Chinese Academy of Sciences, Beijing 100190, China

Huawei Technologies Co., Ltd., Shenzhen 518129, China

University of Sydney, Sydney, NSW 2006, Australia

*Correspondence: gaomingjin@ict.ac.cn (M.G.); shenrujing@ict.ac.cn (R.S.)

Received: October 20, 2022; Revised: January 20, 2023; Accepted: January 24, 2023; Published Online: January 31, 2023; https://doi.org/10.1016/j.xinn.2023.100386

ª2023 The Authors. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Citation: Gao M., Wan L., Shen R., et al., (2023). SparkLink: A short-range wireless communication protocol with ultra-low latency and ultra-high reliability. The Innovation 4(2), 100386.

Dear Editor,

Short-range wireless communications have been widely used in our daily life, but

the pursuit of a better communication experience never stops, leading to the

more stringent requirements of emerging applications.

For example, remote

control applications such as telesurgery require a delay of less than 1 ms.

Indus-

trial closed-loop control applications such as automatic assembly lines have a

reliability requirement of at least 99.999%.

These stringent requirements open

up a new racetrack for the development of short-range wireless communication

protocols.

In this letter, we report a short-range wireless communication protocol,

SparkLink, with ultra-low latency and ultra-high reliability. The key technologies

of SparkLink and the corresponding typical applications in different scenarios,

including smart cars, intelligent manufacturing, smart terminals, and smart

homes, as shown in Figure 1, are introduced.

ULTRA-LOW LATENCY

To tackle the latency challenges faced by various applications, SparkLink has

chosen cyclic-preﬁx orthogonal frequency division multiplexing (CP-OFDM) wave-

form with an ultra-short frame structure and a ﬂexible scheduling scheme of time-

domain resources, and has a variable transmission delay as low as 20.833 ms.

Ultra-short frame structure

To reduce the transmission latency, the length of each radio frame tends

to be short. However, the reduction of frame length is constrained by the

overhead symbols in each frame, especially in the time division duplex

(TDD) scheme adopted by SparkLink. To tackle this issue, SparkLink designs

a frame structure with 48 frames in one superframe, where each frame

shares overhead symbols in the superframe. As a result, the number of over-

head symbols in each frame is substantially reduced. The length of each

frame is 1/48 of the superframe length and is equal to 20.833 ms. To better

Figure 1. Typical applications of SparkLink in different scenarios, including smart cars, intelligent manufacturing, smart terminals, and smart homes

ll The Innovation 4(2): 100386, March 13, 2023 1

LETTER

illustrate the frame structure, we introduce the concept of grant (G) and ter-

minal (T) nodes. In SparkLink, a G node acts as a central transmitter and

receiver of wireless radio signals, manages and schedules the transmissions

of a group of T nodes. A T node transmits and receives signals according to

the scheduling of the G node. Each frame of SparkLink consists of G/T sym-

bols (information symbols carrying data transmitted from G/T nodes to T/G

nodes), an SG/ST symbol (a special G/T symbol as well as overhead sym-

bol), and GAPs (gaps between G and T symbols). Figure 2A shows an

example of the frame structure. Based on this novel frame structure,

SparkLink can achieve ﬂexible latencies by selecting different transmission

periods for the information carrying packets, where the minimum latency

is 20.833 ms.

Flexible scheduling scheme of time-domain resource

To meet different low-latency requirements of various applications,

SparkLink exploits a ﬂexible scheduling scheme of time-domain resources

that corresponds to different sizes of packets. The minimum scheduling units

for small and large packets are equal to the duration of one (20.833 ms) and 6

frames (125 ms), respectively. Based on the minimum scheduling units, the

transmission period can be determined. Speciﬁcally, the transmission period

of small packets is equal to the minimum scheduling unit. The transmission

period of large packets is a multiple of the minimum scheduling units, which

can be equal to 6, 12, .,48frames.Figure 2A depicts the example of the

scheduling scheme for small packets. The minimum duration between two

G symbols colored orange is the transmission period, which is one frame

(20.833 ms).

ULTRA-HIGH RELIABILITY

To meet the stringent reliability requirements of emerging applications,

SparkLink supports ultra-reliable wireless communications by adopting error-

correcting code schemes and hybrid automatic repeat-request (HARQ)

schemes.

Coding scheme

SparkLink adopts the Polar code to correct errors, which has been proven to

achieve the channel capability for large code lengths

and has a superb perfor-

mance when correcting random errors. To enhance the error-correcting perfor-

Figure 2. Key technologies of SparkLink to achieve

ultra-low latency and ultra-high reliability (A) An

example of superframe, where the scheduling

scheme of time-domain resource for small packets

are adopted. (B) Reliability performance of Polar

(SparkLink, 1,024 bits code length) and LDPC (Wi-Fi 6,

1,296 bits code length) under AWGN, where block size

is 1,296 bits and code rate is 0.8.

mance of traditional Polar codes, SparkLink

adopts cyclic redundancy check (CRC)-assisted

Polar codes with successive-cancellation list

(SCL) decoders, where CRC can help SCL de-

coders to select the most likely decoding path.

Figure 2B compares the reliability perfor-

mance of codes used in SparkLink and Wi-Fi 6,

where low-density parity check (LDPC) codes

are used in Wi-Fi 6. With the same code rate, Po-

lar codes with CRC-assisted SCL decoding algo-

rithms always outperform LDPC codes with log

likelihood ratio-based belief propagation (LLR-

BP) decoding algorithms.

Retransmission scheme

Although the SparkLink coding scheme can

reduce error rate by a large margin, errors still

occur due to time variability of channels, multi-

path effect, and other unpredictable interfer-

ences. To confront this issue, HARQ is deployed

in SparkLink to improve the reliability while decreasing the number of

retransmissions.

In traditional ARQ schemes, if transmission errors occur, the receiver aban-

dons packets with errors and requests a retransmission from the transmitter.

Note that the ARQ scheme may waste useful information in the original transmis-

sion. To reuse the information, HARQ combines the information of packets in the

original transmission and the retransmission and acquires channel gains from

the combination. As a result, SparkLink with HARQ has a signiﬁcant reliability per-

formance gap to the ARQ scheme. Speciﬁcally, when the number of retransmis-

sions is 3, SparkLink with HARQ obtains a 7 dB gain compared with the ARQ

scheme, and the gain increases as the number of retransmissions increases.

TYPICAL SCENARIOS AND APPLICATIONS OF SparkLink

With the outstanding performance in terms of latency and reliability, the

SparkLink protocol can be applied in numerous applications. In the following sec-

tion, we introduce the typical applications supported by SparkLink in four sce-

narios, namely smart cars, intelligent manufacturing, smart terminals, and smart

homes.

SparkLink in smart cars

Replacing wired communications by wireless communications is an important

trend in smart cars. Currently, most in-car communication protocols depend on

thewiringharness,suchasCAN,FlexRay,andMOST.

5,6

It is noted that the wiring

harness is the third heaviest component in a car and comprises 50% of the labor

cost for the entire car.

Considering the necessity of replacement and the require-

ment of latency and reliability in smart cars,

SparkLink aims at not only replacing

wired communications but also achieving performance in terms of latency and

reliability comparable to wired communications. A typical example is active noise

canceling (ANC), which can be used to neutralize background noise and make

drivers concentrate on driving. ANC has an end-to-end transmission delay require-

ment of around 20 ms, which can be facilitated by SparkLink.

Currently, SparkLink

has also demonstrated the advantage in a number of in-car applications, including

battery management systems (BMSs) and in-vehicle infotainment (IVI).

SparkLink in intelligent manufacturing

Driven by industrial transformation and upgrading, intelligent

manufacturing is in urgent need that has applications with strict latency

LETTER

2The Innovation 4(2): 100386, March 13, 2023 www.cell.com/the-innovation

www.the-innovation.org

and reliability requirements and offers SparkLink a great opportunity. For

example, to conduct real-time and accurate control in the industrial

closed-loop system, SparkLink can meet the latency requirement within

the ms level and a reliability requirement of 99.999%.

Another example

is the automated guided vehicle (AGV), which is mainly used to transport

goods in warehouses. SparkLink maintains a radio link in a low-latency

(less than 20 ms) and reliable (99.9%) way to prevent accidents and dam-

ages of the goods. With the help of SparkLink, not only the strict require-

ments of applications but also the ﬂexible deployment requirements of

machineries can be fulﬁlledintheﬁeld of intelligent manufacturing.

SparkLink in smart terminals

Smart terminals such as phones, watches, bracelets, earphones, and tablets

are gaining ubiquity in our daily life. Seamless collaboration between these termi-

nals is critical to the user experience, which puts forward high requests to short-

range wireless communications. For example, for the ultimate audio experience,

the lossless audio transmission between a phone and earphones is required.

SparkLink can transmit the 96 kHz 324 bits lossless audio within 10 ms and

can ensure the time synchronization between the left and the right earphones

within the ms level. For the ultimate gaming experience, multi-player mobile

games require real-time interactions between multiple mobile terminals.

SparkLink can meet the end-to-end latency requirement of less than 100 ms

and can ensure a jitter of the mobile game less than 2 ms. Besides the applica-

tions with stringent requirements, SparkLink can also serve traditional applica-

tions, such as multi-screen collaboration.

SparkLink in smart homes

In smart homes, households are usually interconnected by current short-range

wireless communications such as ZigBee, Wi-Fi, and Bluetooth.

Households

such as door locks, televisions, and lights can be controlled remotely by the

homeowner. However, the emerging demands for the ultimate experience in

smart homes create many applications with stringent requirements for latency

and reliability. For example, 8K videos, the current highest resolution available

for commercial-grade videos, will power the home theater to deliver astounding

entertainment experiences. To avoid a blurry screen and getting stuck playing the

8K video, SparkLink ensures high speed transmission with reliability of 99.999%

and an end-to-end transmission delay of less than 10 ms.

Besides the applica-

tions with stringent requirements, traditional applications in smart homes can

still be supported by SparkLink, such as visual doorbells and automatic lighting

control.

CONCLUSION

This paper reports a novel short-range wireless communication protocol

SparkLink with ultra-low latency and ultra-high reliability. Enabled by a ﬂexible

frame structure, SparkLink has a variable transmission delay starting as low as

20.833 ms. Moreover, by adopting Polar codes and HARQ schemes, SparkLink

can support innovative applications with a reliability requirement of 99.999%.

Due to the outstanding performance in terms of latency and reliability,

SparkLink can support lots of typical applications in a variety of scenarios,

including smart cars, intelligent manufacturing, smart terminals, and smart

homes. To offer ultimate service experience, the evolution of SparkLink is still

challenging. In the upcoming versions, SparkLink will include extended features,

such as mesh networking and high-accuracy positioning. We expect to see more

exciting progress of SparkLink in the near future.

REFERENCES

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2. She, C., Sun, C., Gu, Z., et al. (2021). A tutorial on ultrareliable and low-latency communica-

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4. Arikan, E. (2009). Channelpolarization: a method for constructing capacity-achieving codes

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5. Ixia. (2014). Automotive Ethernet: An Overview, https://support.ixiacom.com.

6. Buscemi, A., Turcanu, I., Castignani, G., et al. (2021). CANMatch: a fully automated tool for

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7. Clavier, A.G. (2004). “Wire”versus “wireless”communication. IEEE Microw. Mag. 5,42–44.

8. Chen, K.C., Lin, S.C., Hsiao, J.H., et al. (2021). Wireless networked multirobot systems in

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9. Marcos Amoroso, M., Moraes, R., Medeiros de Araujo, G., et al. (2021). Wireless network

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10. Huawei Technology. (2021). All-optical Quality Bearing Technology for 8K Ultra HD Videos,

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ACKNOWLEDGMENTS

This workis supported in partby Youth InnovationPromotion Association,Chinese Acad-

emy of Sciences, in part by Beijing Municipal Science & Technology Program under grant

Z221100007722014, and in part by Zhejiang Key Research Program under grant

2021C01040.

DECLARATION OF INTERESTS

The authors declare no competing interests.

LETTER

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Performance Evaluation of Sparlink