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Simultaneous Transmission Access Boosting Low-latEncy

STABLE

It is predicted that mobile devices such as connected cars and drones which require low latency for Internet-of-things (IoT) will rapidly spread in accordance with extensive progress of IoT society.

The frequency band that is suitable for accommodating mobile IoT devices is from UHF band to 6 GHz, which have relatively low propagation loss of radio waves even if the waves are obstructed by high buildings. However, these frequency resources have almost all been allocated to existing systems. Hence, further improvement of frequency utilization efficiency is vital in order to accommodate the huge number of mobile IoT devices with low latency by making good use of limited frequency resources.

STABLE (Simultaneous Transmission Access Boosting Low-latEnc) is a novel radio access technique that can significantly improve radio utilization efficiency and solve the problem of frequency resources shortages.

In fact, by conducting experiments of STABLE in Yokosuka Research Park (YRP), we confirmed and demonstrated that STABLE enhanced the radio utilization efficiency 2.5 times higher than conventional systems.

The purpose of the demonstrated technique is to realize massive connection and low latency simultaneously. We expect that the development of STABLE will help the implementation of next-generation wireless communication systems that can accommodate the huge number of mobile IoT devices that need real-time control such as connected cars.

Technical Description

The fundamental technologies of STABLE consist of Grant Free (GF) and Non-orthogonal Multiple Access (NOMA).

GF is used for the realization of low latency communications.

In conventional access techniques, devices necessitate "grant", which is permission obtained from the base station (BS) for transmitting the signal, to send its payload to the BS. The procedure of acquiring "grant" causes the communication to delay about 10 ms. On the other hand, GF permits the devices to send the payload directly without acquiring "grant".

In STABLE, GF is implemented by having devices send Data Signal (DS) with Reference Signal (RS). DS is used for conveying payload. RS is used for device identification as well as channel estimation .

In order to realize the massive connection, we employ NOMA, which is one of the most prominent techniques to accommodate the huge number of devices. NOMA lets multiple devices share the same radio resources. In addition, NOMA can reduce communication latency in addition to enabling massive connection because NOMA allows multiple devices to send signals simultaneously without waiting time. However, when employing NOMA, the BS needs to perform interference suppression and cancellation techniques to demodulate each signal from superimposed signals simultaneously transmitted from multiple devices.

STABLE used in the experiment employed Successive Interference Cancellation (SIC) as the interference suppression and cancellation technique. SIC reconstructs the received signal that has the largest power in superimposed signals and then removes them from the superimposed signals. The reconstructed signal is called a replica. By repeating this procedure, each signal can be separated and demodulated from the superimposed signals. While SIC separates the signal recursively, we have also researched Parallel Interference Cancellation (PIC) that demodulates all devices' signals simultaneously. We have developed the PIC so that 10 devices can share the same radio resources and their signals can be separated and demodulated.

Moreover, in STABLE, diversity and retransmission techniques have also been researched to stabilize the communication besides GF and NOMA. The researched techniques were proposed not only in presentations of international conferences but also in 3GPP as a contribution. In addition, we conducted demonstration experiments with companies.

Glossary

STABLE

A generic name for radio communication techniques including radio signal configuration technology and the interference suppression and cancellation techniques that are newly developed to achieve simultaneous connection from multiple devices in the same radio resources with low latency.


3GPP

The 3rd Generation Partnership Project (3GPP) unites 7 telecommunications standard development organizations (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC), known as "Organizational Partners" and provides their members with a stable environment to produce the Reports and Specifications that define 3GPP technologies. (from 3GPP web site)


5G

In 5th Generation Mobile Communication (5G), Enhanced Mobile BroadBand (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), massive Machine-Type Communications (mMTC)have been defined. Regarding eMBB and URLLC, the specification was completed with Release 15 in June 2018. The specification of mMTC will be completed with Release 16 in December 2019. Note that mMTC does not require low latency. The latency of mMTC is 10 s. (3GPP TR 38.913 V14.3.0)


NOMA

Non-Orthogonal Multiple Access (NOMA) permits devices to share the same radio resources whereas Orthogonal Multiple Access (OMA) allocates radio resources exclusively to each device by dividing the radio resources in the frequency, time, space and code domain.


Interference suppression and cancellation techniques

When multiple devices send signals to a base station in uplink using the same frequency and time resources in NOMA, the base station needs to demodulate the superimposed signals using interference suppression and cancellation techniques. These techniques suppress and remove the interference signal consisting of the superimposed signal to recover the desired signals. In STABLE, 2 techniques, Successive Interference Cancellation (SIC) and Parallel Interference Cancellation (PIC) are employed. SIC successively demodulates each signal in descending order of received power In PIC, all device's signals are simultaneously demodulated.

Members

Publications

International standard proposal
  1. National Institute of Information and Communications Technology、NTT DoCoMo , other companies and institutes、"WF on grant-free for UL URLLC (R1-1703788)"、3GPP TSG RAN WG1 #88 meeting、February 2017.
  2. National Institute of Information and Communications Technology、"UL grant free transmission for URLLC (R1-1705530)"、3GPP TSG RAN WG1 #88bis meeting、March 2017.
  3. National Institute of Information and Communications Technology、"UL grant free transmission for low latency (R1-1707684)"、3GPP TSG RAN WG1 #89 meeting、May 2017.
  4. National Institute of Information and Communications Technology other companies and institutes、"WF on evaluation assumption on UL transmission without UL grant in a DCI (R1-1709824)"、3GPP TSG RAN WG1 #89 meeting、May 2017.
  5. National Institute of Information and Communications Technology、"Resource configuration for UL transmission without grant (R1-1711253)"、3GPP TSG RAN WG1 NR Ad-Hoc#2 meeting、July 2017.
  6. National Institute of Information and Communications Technology、"DMRS design considerations in UL data transmission without grant (R1-1712821)"、3GPP TSG RAN WG1 #90 meeting、August 2017.
  7. National Institute of Information and Communications Technology、"Interleaved Repetition Transmission for UL Grant-Free Transmission (R1-1715656)"、3GPP TSG RAN WG1 #90bis meeting、October 2017.
  8. National Institute of Information and Communications Technology、"LLS assumptions of NR UL NOMA for mMTC scenario (R1-1802896)"、3GPP TSG RAN WG1 #92 meeting、February 2018.
  9. National Institute of Information and Communications Technology、"Receivers for UL NOMA (R1-1804942)"、3GPP TSG RAN WG1 Meeting #92bis meeting、April 2018.
  10. National Institute of Information and Communications Technology、"Tx side processing for UL NOMA (R1-1804941)"、3GPP TSG RAN WG1 Meeting #92bis meeting、April 2018.
  11. National Institute of Information and Communications Technology、"Tx side processing for UL NOMA (R1-1806876)"、3GPP TSG RAN WG1 #93 meeting、May 2018.
  12. National Institute of Information and Communications Technology、"Power control for UL configured grant (CG) transmission (R1-1906117)"、3GPP TSG RAN WG1 #97 meeting、May 2019.
Paper
  1. Masafumi MORIYAMA、Kenichi TAKIZAWA、Masayuki OODO、Hayato TEZUKA、Fumihide KOJIMA、"Experimental Evaluation of a Novel Up-link NOMA System for IoT Communication Equipping Repetition Transmission and Receive Diversity"、IEICE Transactions on Communications, vol. E102-B, No.8, pp.1467-1476, Aug. 2019.
International Conference
  1. Masafumi Moriyama, Kenichi Takizawa, Hayato Tezuka, Masayuki Oodo, Changwoo Pyo, Homare Murakami, Kentaro Ishizu and Fumihide Kojima、"Efficient Radio Access for Massive Machine-Type Communication -An Interleaved Repetition Transmission Technique for Frequency Domain Equalization-"、IEEE Vehicular Technology (Seoul Chapter, Japan Chapter, Singapore Chapter and Taipei Chapter), Asia Pacific Wireless Communications Symposium (APWCS2017) Session C3 - Multiple Access, August 2017.
  2. Chang-Woo Pyo, Kenichi Takizawa, Masafumi Moriyama, Masayuki Oodo, Hayato Tezuka, Kentaro Ishizu, Fumihide Kojima、"A Throughput Study of Grant-Free Multiple Access for Massive Wireless Communications"、The 20th International Symposium on Wireless Personal Multimedia Communications(WPMC)pp528-533, December 2017.
  3. Hayato Tezuka, Masafumi Moriyama, Kenichi Takizawa, Masayuki Oodo, Changwoo Pyo, Homare Murakami, Kentaro Ishizu and Fumihide Kojima、"Hardware Demonstration on An Efficient Radio Access for Massive Machine-Type Communication (mMTC)"、The 20th International Symposium on Wireless Personal Multimedia Communications(WPMC)pp610-616, December 2017.
  4. Masafumi MORIYAMA、Kenichi TAKIZAWA、Masayuki OODO、Hayato TEZUKA、Fumihide KOJIMA、" Experimental Evaluation of a Low Latency UL-NOMA System Employing Repetition Transmission"、APWCS-2018, August, 2018 
  5. Hayato TEZUKA、Masafumi MORIYAMA、Kenichi TAKIZAWA、Masayuki OODO、Fumihide KOJIMA、"Performance Evaluation on UL-NOMA for mMTC Using Hardware Implementation"、APWCS-2018, August 2018. 
  6. Masafumi MORIYAMA、Kenichi TAKIZAWA、Masayuki OODO、Hayato TEZUKA、Fumihide KOJIMA、"An Improvement of Channel Estimation for Up-link NOMA Systems"、WPMC-2018、pp.112-117, November 2018. 
  7. Hayato TEZUKA、Masafumi MORIYAMA、Kenichi TAKIZAWA、Masayuki OODO、Fumihide KOJIMA、"Evaluation of a novel UL-NOMA system in fading environments"、WPMC-2018、pp.262-267, November 2018.
  8. Masafumi MORIYAMA、Kenichi TAKIZAWA、Masayuki OODO、Hayato TEZUKA、Fumihide KOJIMA、"Experimental Evaluation of UL-NOMA System Employing Correlated Receive Diversity"ICNC-2018、pp.879-884, February 2019.
  9. Hayato TEZUKA、Masafumi MORIYAMA、Kenichi TAKIZAWA、Fumihide KOJIMA、"A UL-NOMA system providing low E2E latency"、APWCS-2019、 August 2019.
  10. Masafumi MORIYAMA、Kenichi TAKIZAWA、Hayato TEZUKA、Fumihide KOJIMA、"Transmit Power Control using Fading Prediction for TDD-UL-NOMA Systems"APWCS-2019、August 2019.
Prize

Masafumi MORIYAMA、Kenichi TAKIZAWA、Masayuki OODO、Hayato TEZUKA、Fumihide KOJIMA、"An Improvement of Channel Estimation for Up-link NOMA Systems"、WPMC2018 Best Paper Award, November 2018.

Press release

NICT web site
"周波数利用効率を2.5倍改善する無線アクセス技術STABLEの野外実証に成功"(Japanese) August 2018

Newspaper

Nihon Keizai Shimbun、"5Gで多数の機器接続"、page.9、 (Japanese) August 2018.

Standardization Activities

3GPP TR 38.812 V16.0.0

3rd Generation Partnership Project;Technical Specification Group Radio Access Network; Study on Non-Orthogonal Multiple Access (NOMA) for NR (Release 16), Dec. 2018.

News & Information

The latest research results were presented in 16th IEEE Asia Pacific Wireless Communications Symposium (APWCS2019) held in Singapore from August 28 to August 30th, 2019.

  1. Hayato TEZUKA、Masafumi MORIYAMA、Kenichi TAKIZAWA、Fumihide KOJIMA、"AUL-NOMA system providing low E2E latency"、APWCS-2019、30,Aug.2019.
  2. Masafumi MORIYAMA、Kenichi TAKIZAWA、Hayato TEZUKA、Fumihide KOJIMA、"Transmit Power Control using Fading Prediction for TDD-UL-NOMA Systems"APWCS-2019、30,Aug.2019

Message

As low latency and massive connection are realized by STABLE which is one of the candidates of next-generation mobile communication systems, we would like to look for the partners that are willing to collaborate research and demonstration experiments with us through brainstorming, cooperative research and so on.

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