Panel Discussion @NoMA Workshop · 05/10/2017 · –Some implementation from industry – field...

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Panel Discussion @NoMA Workshop

Starts at 4:30 pm

HUAWEI TECHNOLOGIES CO., LTD., Proprietary

Outline of the Panel Discussion

• Building connections between academic and industry

– DL NoMA in 3GPP

– UL NoMA in 3GPP

– Some thinking towards future – Unified framework

– Some implementation from industry – field trials introduction from DoCoMo

• Open minded discussion towards future study

– What are your most interested application scenarios for NoMA?

– What are the most important metrics to evaluate NoMA in your mind?

– What are your most interested features for NoMA design?


Discussion on NoMA in Standardization


• Three categories of MUST schemes (power domain reflected in compound modulation)

DL NoMA (MUST) in Rel-14 LTE WI in 3GPP

In MUST Category 1, coded bits of two or more co-scheduled UEs are independently mapped to component constellation symbols but the composite constellation does not have Gray mapping.

In MUST Category 2, coded bits of two or more co-scheduled UEs are jointly mapped to component constellations and then the composite constellation has Gray mapping.

In MUST Category 3, coded bits of two or more co-scheduled UEs are directly mapped onto the symbols of a composite constellation (the power domain superposition is done implicitly during the bit-to-symbol mapping).

Figures from “Non-Orthogonal Transmission Technology in LTE Evolution,”IEEE COMMAG, July 2016


Candidate Schemes Observed in Rel-14 NR SI in 3GPP MA scheme Company Full Name Main Features Proposed Usage

SCMA [R1-162155] Huawei Sparse code multiple access Symbol-level spreading UL/DL

PDMA [R1-164247] CATT Pattern division multiple access Symbol-level spreading UL/DL

LDS-SVE [R1-164329] Fujitsu Low density spreading-signature vector extension Symbol-level spreading UL/DL

MUSA [R1-162226] ZTE Multi-user shared access Symbol-level spreading UL

NCMA [R1-162517] LGE Non-orthogonal coded multiple access Symbol-level spreading UL

NOCA [R1-165019] Nokia Non-orthogonal coded access Symbol-level spreading UL

FDS [R1-162385] Intel Frequency domain spreading Symbol-level spreading UL

RSMA [R1-163510] Qualcomm Resource spread multiple access Symbol-level scrambling UL

RDMA [R1-167535] MTK Repetition division multiple access Symbol-level scrambling UL

GOCA [R1-167535] MTK Group orthogonal coded access Symbol-level scrambling UL

IGMA [R1-163993] Samsung Interleave-grid multiple access Symbol-level interleaving UL/DL

NOMA [R1-163111] DCM Non-orthogonal multiple access Symbol-level superposition UL/DL

LSSA [R1-164869] ETRI Low code rate and signature based shared access Bit-level interleaver UL

IDMA [R1-165021] Nokia Interleaver division multiple access Bit-level interleaver UL

LCRS [R1-162385] Intel Low code rate spreading Bit-level spreading UL


Agreed Objectives of Rel-15 UL NoMA SI in 3GPP Non-orthogonal multiple transmission scheme

Transmitter side signal processing schemes for non-orthogonal multiple access [RAN1]:

• Modulation and symbol level processing, including spreading, repetition, interleaving, new constellation mapping, etc.

• Coded bit level processing including interleaving and/or scrambling, etc.

• Symbol to resource element mapping, sparse or not, etc.

• Demodulation reference signal. Other signal is not excluded.

Receivers for non-orthogonal multiple access: [RAN1, RAN4]

• MMSE receiver, successive/parallel interference cancellation (SIC/PIC) receiver, joint detection (JD) type receiver, combination of SIC and JD receiver, or other receivers.

• The study should consider performance, receiver complexity, etc.

Procedures related to the non-orthogonal multiple access [RAN1]

• UL transmission detection

• HARQ, including transmission scheme, feedback scheme, and combining scheme

• Link adaptation MA signature allocation/selection

• Synchronous and asynchronous operation

• Adaptation between orthogonal and non-orthogonal multiple access

Link and system level performance evaluation or analysis for non-orthogonal multiple access continued from performance metrics identified from

Rel-14. The benchmark for comparison is OFDM contention based multiple access. Realistic modelling of Tx/Rx impairment including potential PAPR

issue, channel estimation error, power control accuracy, collision, etc. should be considered. [RAN1]

• Traffic model and Deployment scenarios of eMBB (small packet), URLLC and mMTC

• Device power consumption

• Coverage (link budget)

• Latency and signalling overhead

• BLER reliability, capacity and system load

• Physical abstraction (link-to-system mapping model)

Transmitter

Receiver

Procedure

Evaluation


• How to make good use of the unified framework to converge the study?

Suggestion for Component-wise Study – Transmitter

First to identify for each scheme, which component block has UE specific signature design

Each company justify the benefit of the component block with UE specific design, comparing with a corresponding baseline

Multiple options proved of benefit can be recommended within each component block

FEC Bit-level

Interleaver /Scrambler

Modulated Symbol Sequence Generator

Symbols to RE Mapping

IFFT

Bit level operations Symbol level operations OFDM operations

Options

UE specific scrambler (LTE)

UE specific interleaver

Options

Single tone or multi-tone modulation

UE specific symbol spreading

User specific symbol interleaver/scrambler

Sparse/non-sparse resource mapping

Power adjustment


Suggestion for Component-wise Study – Receiver

• How to converge the study of advanced receiver?

… SU Detector

such as

MF/MMSE

FEC

Decoder

……

Signal

Rebuild

… …

SU Detector

such as

MF/MMSE

FEC

Decoder

……

Signal

Cancel

…

…

…

De-

Mapping

De-

Mapping

……

Decoded

bits

Decoded

bits

Received

symbols

2nd Stage

1st Stage

…

Received

symbols

MU

Detector

such as

MPA/EPA/

MMSE/ESE

FEC

Decoder

…

Decoded

bits

…Signal

Rebuild

… …

MU

Detector

such as

MPA/EPA/

MMSE/ESE

……Signal

Cancel

…

…

…

2nd Stage

1st Stage

De-

Mapping

De-

Mapping

……

…FEC

Decoder

……

FEC

Decoder

LLR of undecoded bit streams

Decoded

bits

…

FEC

Decoder

SU detector + hard SIC MU detector + hybrid soft/hard PIC


Discussion on NoMA in Field Trials Presentation from Yoshihisa Kishiyama, NTT DoCoMo


Discussion on Open Questions


Open Questions Discussion


– Applicability of NoMA to WiFi, especially for cost of 2-5 dollars with unlicensed band • Prof. Ding: #UE can be supported can be boosted by NoMA given limited # of channels; so improved

connectivity • Dr. Ma: many features defined for licensed band can be reused for unlicensed band, NoMA is one

example, but some special care needs to pay. • Prof. Hanzo: Current WiFi could not work very well with a large crowd, so any improvement in overall

connectivity/capacity should be considered. NoMA with advanced detectors/receivers, different from linear MMSE receiver, can work with more rank efficient scenarios and improve WiFi capacity. Moreover, there is duality of receiver side and transmit side which implies by applying all types of iterative receivers, not so stringent design required.

• Prof. Choi: the reason of NoMA’s popularity is due to its nature as generalization of OMA, it can be applied to WiFi or any other communication system.

• Kishiyama-san: cellular network favors NoMA application due to its more accurate power control/link adaptation, but in WiFi, these conditions are not the same, which needs to be considered.


Open Questions Discussion • Open minded discussion towards future study

– What are your most interested application scenarios for NoMA? – What are the most important metrics to evaluate NoMA in your mind? – What are your most interested features for NoMA design?

• Kishiyama-san: massive connectivity is the most beneficial scenario; as operator, performance is more important than complexity; NoMA + full duplex/dynamic TDD is of interest to deal with the inter-user interference

• Prof. Hanzo: varied services, delay-sensitive/non-sensitive, power domain superposition at different SNR level with precise power control, PIC with iterative information exchange may make life easier than hard SIC in the sense of ordering users and reduce latency

• Prof. Ding: in general, like to think about applications that haven’t been discussed; the current main scenarios such as NoMA + MIMO are mainly to show NoMA are compatible; different scenarios shall have different metrics (delay, thp, connectivity); would like to reverse the question as what other features defined outside NoMA can facilitate NoMA design jointly. Some examples of new applications V2X worth considering.

• Dr. Ma: NoMA supposed to be used in all scenarios such as eMBB, URLLC, and mMTC. In particular interest, NoMA + grant-free, due to benefit of signaling overhead/energy consumption/latency reduction, which are important for machine type devices. For DL, UE experience in multi-cell is important and reduce handover. In general, SE is still the key for all scenarios, but KPI is also related to scenarios. For example, UE drop rate given UE service requirement can be a measure for DL and URLLC, for UL, the overall connectivity in a system given bandwidth/time, etc. About features, spatial multiplexing and full duplex should be the features jointly considered with NoMA. Joint optimization is interesting topic.

• Prof. Choi: two key words in feature design, i.e., power v.s. energy domain noma + interference. Two types of interferences, strong (in power domain noma) – receiver can detect and cancel – no impact in theory and thus better than weak interference. HARQ process design can be considered.




– Grant-free access is one important scenario for NoMA, but it seems to be contradictory with high capacity. How can we balance grant-free access and high capacity. For instance, for 10 year design, how to balance the two.

• Prof. Ding: this should depends on scenarios. For URLLC, delay and reliability is more important than capacity; for IoT, connectivity is more important than SE. Multiple modes can be supported in the future and applied with network slicing as a way to accommodate different schemes for different scenarios.

• Dr. Ma: For grant-based, if you have ideal scheduler, then it is always the best, however, in practice it costs resources to do scheduling. If the packet size is small, then the ratio of overhead in the scheduling overhead is large. Instead, grant-free NoMA can solve this with robust transmission and the efficiency can be achieved by multiplexing a group of users instead of for each user to achieve high SE. For NoMA, different modes shall be supported.

• Prof. Choi: wireless communications need to combat the fading, and for unknown environment, it takes time/resource to understand environment.

• Prof. Hanzo: scheduling based can give best user more resource to achieve total high capacity, but for fairness and delay limited services, it is not. Depending on the service type, e.g., uplink buffer-aided solutions should be investigated.



• Open minded discussion towards future study – NoMA can be considered as sending data simultaneous. What if the data is correlated? What is the

theoretical limits how good NoMA can do in this scenario?

• Prof. Choi: there are some papers addressing NoMA for multi-cast. And we are generalizing the problem which may cover the issue. Another relative example is in sensor networks, which is under investigation.

• Prof. Hanzo: there is discussion on Research Gate.

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Panel Discussion @NoMA Workshop · 05/10/2017 · –Some implementation from industry – field...

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