The document summarizes innovations to the medium access control (MAC) layer from the SPEED-5G project to support enhanced dynamic spectrum aggregation (eDSA). It describes a MAC framework to coordinate scheduling across radio access technologies at the MAC level. It also presents two novel MAC designs - the dynamic channel selection MAC (DCS-MAC) and filter bank multicarrier MAC (FBMC-MAC) - along with simulation results comparing their performance to legacy systems like LTE and WiFi. The conclusions indicate both MAC designs outperform existing technologies but DCS-MAC is generally better for licensed bands while FBMC-MAC is more suitable for unlicensed bands due to its listen-before-talk approach.

1. SPEED-5G Project
London, March 7th 2018
Benoit Miscopein
SPEED-5G MAC innovations
www.speed-5g.eu

2. 48
Outline
4 MAC framework to support eDSA
4 SPEED-5G MAC designs description
4 MAC simulation results
4 Conclusion
SPEED-5G workshop, London, 07/03/2018

3. MAC framework
4 eDSA capable MAC framework has been defined
➨ Inter-RAT scheduling done at MAC level, where logical channels are
steered on the different air interfaces (aggregation split @ MAC)
49SPEED-5G workshop, London, 07/03/2018

4. MAC framework
4 eDSA capable MAC framework has been defined
➨ Inter-RAT scheduling done at MAC level, where logical channels are
steered on the different air interfaces (aggregation split @ MAC)
50
SoTA : 3GPP LWA
SPEED-5G workshop, London, 07/03/2018
HARQ HARQ
DL-SCH
on CCi
...
Segm.
ARQ etc
Multiplexing UEa Multiplexing UEn
Unicast Scheduling / Priority Handling
Logical Channels
MAC
Radio Bearers
Security Security...
RLC
PDCP
ROHC ROHC...
Segm.
ARQ etc
...
Transport Channels
Segm.
ARQ etc
Security Security...
ROHC ...
Segm.
ARQ etc
...
...
...
...
DL-SCH
on CCj
HARQ HARQ
DL-SCH
on CCk
...
DL-SCH
on CCl
HARQ HARQ
DL-SCH
on CCm
...
Segm.
ARQ etc
Multiplexing UEn Multiplexing UEz
Unicast Scheduling / Priority Handling
Security...
ROHC...
Segm.
ARQ etc
...
Segm.
ARQ etc
Security Security...
ROHC ROHC...
Segm.
ARQ etc
...
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DL-SCH
on CCn
HARQ HARQ
DL-SCH
on CCo
...
DL-SCH
on CCp
Split
MeNB SeNB
User-plane
split/switch
at PDCP

5. MAC framework
4 eDSA capable MAC framework has been defined
➨ Inter-RAT scheduling done at MAC level, where logical channels are
steered on the different air interfaces (aggregation split @ MAC)
51
SPEED-5G proposal
SPEED-5G workshop, London, 07/03/2018

6. MAC framework
52
HMAC
LMAC
Configuration
Sensing&measurements
management
UnlicensedLicensed
PHY
Scheduling
SPEED-5G MAC framework
Lightly-Licensed
d/cRRM
Higher layers protocol
stack
Inter-RAT
coexistencecoord.
Data plane
Monitoring
plane
Control/configuration
plane
TX/RX
Inter-RATscheduling
RRC and RRM
configurations
RRC signalling
Bufferstatusreports
Scheduling
TX/RX
Scheduling
TX/RX
AI #1 AI #2 AI #n
SPEED-5G workshop, London, 07/03/2018

7. SPEED-5G MAC innovations
4 eDSA capable multi-RAT framework
➨ Inter-RAT coordination at the MAC level to aggregate heterogeneous spectrum resources
➨ Seamless traffic (control and user data) steering from one RAT to the other
➨ Management of contextual PHY and MAC measurements for RRM (aka monitoring plane)
➨ Support of legacy systems (Wifi & LTE-A) and integration of any 5G air interface variants
4 2 novel MAC proposals for eDSA capable RATs
➨ DCS-MAC
● TDD access supporting multi-channel operation in heterogeneous spectrum, based on
dynamic channel selection
➨ FBMC-MAC
● Beacon-enabled TDD access based on Listen-Before-Talk for unlicensed spectrum
operation, assuming FBMC PHY
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8. MAC designs description
DCS MAC
FBMC MAC
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9. DCS-MAC main characteristics
4 Multi-channel operation
4 Time slotted access with TDD
4 Dynamic channel selection
4 Decentralized decision-making
4 Cluster-based architecture
4 Modified RACH design
Physical channel = time
slot + frequency channel
combination
Frame length
Multi-frame length
SPEED-5G workshop, London, 07/03/2018

10. DCS-MAC basic operation
4 SC periodically scan all supported channels using a predefined scanning/hopping sequence
4 UEs determine which frequency channel (and when) will be scanned and initiate a
transmission with their SCs (radio bearer establishment)
4 UEs adopt a similar scanning procedure to enable a SC initiated transmission
4 Quality of available channels is continuously monitored by UEs and SCs to maintain an up-to-
date map of channel quality
4 Intra-cell (or inter-cell) handover can be triggered if radio bearers quality is degraded
SPEED-5G workshop, London, 07/03/2018

11. FBMC MAC main features
57
4 Master-slave operation in 5GHz band
4 Beacon enabled TDD MAC frame
4 LBT-based superframe emission by SCs
4 Mix of scheduled and contention
access for UEs
4 OFDMA-like access in DL and UL
(FBMC features)
SPEED-5G workshop, London, 07/03/2018

12. FBMC MAC basic operation
58
4 Frame based access: rigid, unfair in dense layouts but
maximises throughput in non crowded situations
4 Load based access: fairer access due to backoff process
4 Single channel operation with LBT
with variable detection threshold
4 User traffic sent in CFP where SC
allocates resources (DL and UL)
4 Beacon carries most of DL control
traffic: frame format, UE grants,
commands like channel switch
4 DL dedicated command frames
(measurement requests) can be
multiplexed with data
4 UL control (command) frames sent
in CAP w/ multi-channel CSMA
SPEED-5G workshop, London, 07/03/2018

13. MAC simulation results
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14. Methodology
4 Simulations have been run on calibrated system-level simulation tools to get comparable results
4 Common setup and simulations scenarios have been defined to enable comparison of both designs
4 Simulations results compared with legacy (Wifi and LTE) technologies to show the gains of SPEED-5G
4 MAC designs compared to extract guidelines for MAC selection, w.r.t. the context of operation
60SPEED-5G workshop, London, 07/03/2018

15. Simulation parameters
4 Topology:
➨ Outdoor hexagonal grid with ISD= 30 to 100m
➨ 10 UEs per cell
4 Channel model
➨ Extended UMi model w/ and w/o fast fading
➨ Spatially correlated shadowing and LOS/NLOS conditions
4 Traffic pattern
➨ 100% downlink – 80% DL / 20% UL
➨ Full buffer and FTP
4 Interference modelling
➨ Explicit co-channel interference modelling (frequency reuse = 1),
➨ Mask-based out-of-band interference (frequency reuse >1 for FBMC)
4 Considered scenarios
➨ Non-coexistence and coexistence with WiFi systems
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16. Non coexistence scenario
4 UE randomly deployed on the SC
coverage and attachment done on
strongest SC
4 50 runs per simulation
4 1 simulation = 100s
4 All SCs, all UEs and all packets are
modelled, contributing to per device
SINR computation
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17. DCS-FBMC comparison
Non-coexistence scenario (results summary)
4 FBMC-MAC is outperformed by DCS-MAC in terms of DL throughput due to LBT
(reduction of transmit time)
4 FBMC-MAC outperforms DCS-MAC in UL throughput due to SC-SC interference
4 Irreducible delay due to the frame structure leads to higher latency in DCS in low load
scenarios
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MAC design DCS-MAC FBMC-MAC
ISD [m] 30 50 100 30 50 100
DL traffic
Mean delay [ms] 27 20 13.5 12 6.5 4.5
Per-cell SE [bps/Hz] 0.3 0.4 0.75 0.15 0.25 0.5
Area SE [bps/km2/Hz] 370 191 85 206 108 52.5
Access fairness 0.997 0.997 0.998 0.84 0.88 0.92
UL traffic
Mean delay [ms] 113 68 40 29 17 14
Per-cell SE [bps/Hz] 0.02 0.04 0.08 0.05 0.06 0.13
Area SE [bps/km2/Hz] 27 16 10 64 27 15
Access fairness 0.984 0.990 0.989 0.84 0.88 0.92

18. Coexistence with WiFi systems
4 Assumptions
➨ “Wifi” APs dropped in the SPEED-5G
layout (1 AP per SC)
➨ APs implement simplified DCF
protocol and assume saturated mode
in DL (worst case scenario)
➨ No “Wifi” stations deployed
4 Metrics
➨ Statistics of “WiFi” channel
occupancy time
➨ Fairness between SPEED-5G SC and
Wifi on channel occupancy
64SPEED-5G workshop, London, 07/03/2018

19. DCS-FBMC comparison
Coexistence scenario (results summary)
4 FBMC-MAC provides a fairer access than DCS-MAC (LBT enables better
coexistence characteristics)
4 DCS-MAC is more aggressive on channel access compared to FBMC-MAC
but appropriate parameters tuning can provide better fairness
4 Advanced coexistence mechanisms can be incorporated in DCS-MAC to
enable better coexistence capabilities
65
Wifi channel occupancy ratio
SPEED-5G workshop, London, 07/03/2018
MAC designs DCS-MAC FBMC-MAC
ISD [m] 30 100 30 100
Mean delay [ms] 59 26 30 13
Area SE [bps/km2/Hz] 192 58 106 29

20. SPEED-5G vs. legacy systems
4 DCS-MAC and FBMC-MAC have been compared with legacy technologies on identical
scenarios
➨ IEEE 802.11ac for unlicensed spectrum (5GHz)
➨ LTE-A rel. 10 in SISO and w/o aggregation
4 By nature,
➨ FBMC-MAC is close to WiFi as it operates in unlicensed spectrum using LBT
➨ DCS-MAC is closer to LTE-A than WiFi as it targets licensed and lightly licensed spectrum
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21. SPEED-5G MAC designs against SOTA
4 Both designs outperform WiFi (higher ASE, no user outage)
4 DCS-MAC provides better performance than LTE-A (higher ASE and better
cell-edge performance)
67
ASE (bps/km²/Hz)
ISD [m] 30 50 100
WiFi (802.11ac) 111 44 20
LTE-A (Rel.10) 442 190 95
FBMC-MAC 241 125 61
DCS-MAC 554 261 116
Full-buffer DL 100%, ISD=100m Full-buffer DL 100%, ISD=30m
SPEED-5G workshop, London, 07/03/2018

22. Conclusion
4 MAC design in SPEED-5G has been specified
➨ A multi-RAT MAC framework in support of eDSA
➨ Detailed specifications (incl. interfaces and primitives) for the 2 MAC designs have been provided
4 Comparison with legacy technologies show that SPEED-5G designs are promising solutions for dense-
ultra dense deployment
➨ DCS-MAC give better results in licensed/lightly licensed bands.
➨ Due to LBT, FBMC-MAC is more suitable for operation in unlicensed bands where fair coexistence is mandated.
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23. MAC innovations in demonstrations
4 Demonstration 1
➨ MAC framework (w/o aggregation)
➨ HMAC interface with hierarchical RRM entities
➨ FBMC-MAC design implementation
4 Demonstration 2
➨ Full MAC framework with aggregation point @ MAC
➨ Inter-RAT scheduling applied to LTE and WiFi
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24. Thank you for your attention!
70
Acknowledgment:
The research conducted by Speed-5G receives funding from the European Commission H2020 programme under
Grant Agreement N : 671705. The European Commission has no responsibility for the content of this
presentation.
Find us at www.speed-5g.eu
SPEED-5G workshop, London, 07/03/2018