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Understanding MulteFire’s Radio Link
Multefire technology enhances LTE performance by enabling operation in unlicensed spectrum while maintaining strong coverage, capacity, and mobility benefits. It coexists with existing technologies such as LAA and ELAA, offering approximately double the capacity compared to Wi-Fi under similar conditions. Key advantages include improved signal quality, seamless mobility, and efficient resource management, particularly in dense environments.
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Understanding MulteFire’s Radio Link
- 1. Understanding MulteFire’s Radio Link Dr.Tamer Kadous, Radio Workgroup Chair
- 2. Agenda • Coexisting inunlicensed spectrum • MulteFire Technology—extensions added to 3GPP LAA and eLAA • MulteFire performance advantages and results • Summary
- 3. Multiple technologies willcoexist in unlicensed spectrum 1) Licensed-Assisted Access (LAA), also includes enhanced LAA (eLAA); 2) LTE Wi-Fi Link Aggregation (LWA); 3) LTE Wi-Fi radio level integration with IPsec tunnel (LWIP); 4) 802.11ac / .11ad / .11ax / .11ay Wi-Fi4 Evolving for enhanced performance and expanding to new usage models, used today as neutral host Licensed Spectrum Exclusive use Unlicensed Spectrum Shared use Aggregation MulteFire Broadens LTE ecosystem to enhanced and new deployment opportunities, suitable for neutral host LWA2, LWIP3 Targeting mobile operators leveraging existing carrier Wi-Fi deployments LTE-U / LAA1 Targeting mobile operators using LTE in unlicensed spectrum for new small cell deployments anchor
- 4. MulteFire performance advantages 1)Signal-to-interference-plus-noise ratio (SINR); 2) Media Access Control (MAC) Layer; 3) Handover (HO); 4) Radio link failure (RLF) Coverage • Retains LTE’s deep coverage characteristics • Targets control channels to cell edge SINR1 of -6dB • 5-6dB link budget advantage over Wi-Fi Capacity • Leverage LTE link efficiency and MAC2 • Significant gains (2X) over 802.11ac baseline • Comparison with .11ax under investigation Mobility • Brings carrier-grade LTE mobility to unlicensed • Seamless & robust mobility • Service continuity to WAN • Significantly better than Wi- Fi, esp. outdoor, 50 km/h Robustness • More predictable & robust performance than Wi-Fi • Forward HO3 enables recovery when RLF4 • Enhanced RLF4 triggers • Mature SON techniques
- 5. MulteFire technology isbased on 3GPP LAA and eLAA Extends eLAA—uplink & downlink—to operate without anchor in licensed spectrum 3GPP Rel. 13 3GPP Rel. 14 Uplink waveform & channels Flexible frame structure UL 2 HARQ 3 , scheduling enhancements Supplemental downlink + HARQ 3 LBT 4 coexistence in unlicensed Multi-carrier operation Enhanced discovery signals Robust procedures: mobility, paging, RA 1 ... Robust & efficient UL 2 control channels Advanced LTE air-interface LTE TDD MulteFire Alliance Operate without licensed anchor eLAA: +Uplink LAA: Downlink LTE New features 1) Random Access; 2) Uplink; 3) Hybrid automatic retransmission request; 4) Listen before talk
- 6. Flexible frame structuressupporting any UL/DL traffic mix D S U U U U U U U U D D D D D D D D S U D D D D D D S U U U Allows any Uplink (U) or Downlink (D) sub frame mix D S U U U D S U U U0 D S U U D D S U U D1 D S U U U D D D D D3 D S U U D D D D D D4 D S U D D D D D D D5 D S U U U D S U U D6 Maximizes efficiency for any traffic, from uplink- heavy to downlink-heavy D S U D D D S U D D2 D D D D D D D D D D D U U U U U U U U U Rel.14: numerous TDD configurations, Dynamical switching Rel.8: limited TDD configurations, Semi-static switching Dynamic switching between configurations on a per TxOP basis … … … … … … … … … … D S U U U U D D D D … … … … … … … … … … … … … … … … … … … … TxOP1 example with 10 ms TxOP1 example with 10 ms 1) Transmit opportunity (TxOP)
- 7. Flexible frame structurefor more efficient LBT1 Fixed frame structure—wait for next downlink sub-frame (D), fixed to system time Flexible frame structure—any sub-frame can be downlink (D), no need to wait Fixed structure2 Over-the-air U U U D D D D S U U U U U D D D D S U U U U U D D D D S U U U U U D D D DD D U U U U U D D D D D U U U U US S eCCA1 cleared eCCA cleared CCA May lose medium while waiting for D Over-the-air UD D D S U U U U D D D D D D D D UD S eCCA cleared eCCA cleared 1) Listen before talk (LBT) using enhanced Clear Channel Assessment (eCCA); 2) D = Downlink (DL), U = Uplink (UL), and S = Special sub-frame (mix of UL, DL and guard period)
- 8. Uplink scheduling enhancementsimproves performance Efficiently support flexible frame structure …D D D D D D D S U U D S U U U U U U eCCA eCCA TxOP1 Single-TTI UL grant First uplink UL sub-frame that can be granted from same TxOP (n 4) Multi-TTI UL grants Allows multiple UL sub-frames to be granted by a single grant. U Cross TxOP UL grants Enables UL heavy configurations UL sub-frames that cannot be granted within same TxOP 1) Transmit opportunity (TxOP) U
- 9. U D US UU US S Asynchronous UL HARQ handles unknown timing of LBT Synchronous UL HARQ—fixed timing for ACK/NACK and retransmissions Asynchronous UL HARQ—ACK/NACK and retransmissions adapt to actual TxOP from LBT …… D D D D D D D D ACK / NACK RetransmitTransmit … … eCCA eCCA TxOP ACK / NACK RetransmitTransmit S U D D D D D D DS SS S U U U UUUUU U U
- 10. Flexible uplink waveformto meet spectrum requirements Meets PSD1 limits for 5GHz unlicensed with better link budget (coverage) LTE SC-FDM uplink—localized power 1) Power Spectrum Density (PSD) measured in power per spectrum, e.g., dBm/MHz; 2) Power concentrated in one part of the spectrum generally good for uplink coverage—but not if there is PSD limit. RB interlaced—distributed power ………50 RBs in 10Mhz Time Spectrum PSD1 When there is PSD limit, concentrating the power in one part of spectrum may limit TX power.2 Spectrum PSD1 limit One UE UE TX power Time Spectrum ……10 One interlace 10/20 MHz bandwidth is divided into 5/10 interlaces ……10 ……10 ……10 Spreading power over spectrum allows a higher TX power within same PSD limit. Spectrum UE TX power PSD1 PSD1 limit
- 11. Enhanced discovery signalshandles unlicensed operation Increased robustness needed without a licensed anchor used by LAA/eLAA 1) Primary Synchronization Signals (PSS), Secondary Synchronization Signals (SSS), and Physical Broadcast CHannel (PBCH). DD X X X X X … D D U U … DS Backwards compatible — LAA/eLAA understands MulteFire signals Slots Sub-carriers SSS PSS PBCH PBCH+ PBCH+ SSS+ PSS+ Repeats critical symbols1 for faster and more robust acquisition Enables decoding with a single instance for cell edge users Existing symbols … DD D U US X X X X Periodic TX opportunities Repeated symbols
- 12. … … Periodic TXopportunities defined to handle LBT …………… DD X X U D S U DD DD U US X U Periodic TX opportunities downlink Periodic TX opportunities for pre-configured uplink X X DRS Window (up to 10ms) 1) Discovery Reference Signal (DRS), Random Access Channel (RACH), Radio Resource Management (RRM) X X DRS Window (up to 10ms) Paging Window (up to 10ms) UE monitors paging in a window Defined TX windows for critical operations, e.g., DRS, RACH, RRM1
- 13. Introducing PUCCH1 forstandalone operation in unlicensed spectrum 1) Discovery Reference Signal (DRS), Random Access Channel (RACH), Radio Resource Management (RRM) Short PUCCH (sPUCCH) combined with extended PUCCH (ePUCCH Periodic TX opportunities for pre-configured uplink … D D D D D U US U U … D D D U US U U U U … ACK/NACK over sPUCCH Pending ACK/NACK, e.g due to LBT loss Any pending ACK/NACK over ePUCCH TxOPeCCA eCCA sPUCCH for small payloads in part of a special sub-frames (S) ePUCCH for larger payload and high user mux capability ACK/NACK, CSI & SR feedback for DL TX on sPUCCH & ePUCCH
- 14. Robust mobility • Seamlessexperience for various mobility modes • Backward and forward handover supported (as Rel. 12) – Shorter interruption in case of radio link failure from forward handover • Enhancement to radio link failure triggers to operate with contention – Detect missing DRS sub-frames as part of in-sync/out-of-sync measurements • Enhancements for RRM measurements in async. deployments – New measurement gap configurations defined to enable measuring infrequently occurring DRS Mobility Idle Connected Between MulteFire nodes Moving from MulteFire to Macro network Moving from Macro to MulteFire
- 15. Indoor simulations results Baselinewith 2 Wi-Fi operators in an office building, each with 4 access points 1 1) Indoor, single 20 MHz channel in 5 GHz, 80%-20% traffic split between down- and uplink, bursty traffic generated with 4 Mb files arriving with exponential inter arrival times, high traffic load with buffer occupancy at 50% in downlink and 20% in uplink for Wi-Fi only baseline, 4 APs per operator, 2 operators, office building size 120m x 50m, propagation model 3GPP indoor hotspot (InH), Wi-Fi is 802.11ac, MIMO 2x2, no MU-MIMO Wi-Fi operator #1 Wi-Fi operator #2 120m 50m 0 1 2 3 4 Downlink 0 1 2 3 4 Uplink Median throughput gain Wi-Fi only baseline
- 16. 0 1 2 3 4 Uplink 0 1 2 3 4 Downlink Median throughput gain 2Xgain Wi-Fi only baseline MulteFire offers 2X capacity gain over Wi-Fi baseline 1 Wi-Fi performance preserved, sometimes better, when neighbor switch to MulteFire 1) Indoor, single 20 MHz channel in 5 GHz, 80%-20% traffic split between down- and uplink, bursty traffic generated with 4 Mb files arriving with exponential inter arrival times, high traffic load with buffer occupancy at 50% in downlink and 20% in uplink for Wi-Fi only baseline, 4 APs per operator, 2 operators, office building size 120m x 50m, propagation model 3GPP indoor hotspot (InH), Wi-Fi is 802.11ac, MIMO 2x2, no MU-MIMO Wi-Fi operator #1 MulteFire operator 120m 50m
- 17. MulteFire by itselfoffers >2X capacity gain over Wi-Fi 1 Higher gains in MulteFire only deployments, especially in dense scenarios MulteFire operator #1 MulteFire operator #2 50m 120m 0 1 2 3 4 Downlink 0 1 2 3 4 Uplink Median throughput gain Wi-Fi only baseline 2X gain 1) Indoor, single 20 MHz channel in 5 GHz, 80%-20% traffic split between down- and uplink, bursty traffic generated with 4 Mb files arriving with exponential inter arrival times, high traffic load with buffer occupancy at 50% in downlink and 20% in uplink for Wi-Fi only baseline, 4 APs per operator, 2 operators, office building size 120m x 50m, propagation model 3GPP indoor hotspot (InH), Wi-Fi is 802.11ac, MIMO 2x2, no MU-MIMO
- 18. MulteFire offers significantcapacity advantage outdoors 1 Gain over Wi-Fi depends on load and traffic mix, 2X-6X in simulation scenarios Wi-Fi MulteFire 1 2 1 2 1 2 2 1 2 1 2 1 2 1 2 1 0 1 2 3 4 Uplink 0 1 2 3 4 Downlink Median throughput gain Wi-Fi only baseline 2X gain 1) Outdoor, single 20 MHz channel in 5 GHz, 50%-50% traffic split between down- and uplink, bursty traffic generated with 4 Mb files arriving with exponential inter arrival times, medium traffic load with buffer occupancy at 38% in downlink and 51% in uplink for Wi-Fi only baseline, dense cluster deployment, 2 operators, 4 APs each, propagation model 3GPP outdoor scenario with all APs in 50m radius, Wi-Fi is 802.11ac, MIMO 2x2, no MU-MIMO
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- 20. Based on 3GPPstandards MulteFire Technology is based on 3GPP LAA and eLAA Similar performance & coexistence as LAA/eLAA in unlicensed Extends eLAA—uplink & downlink—to operate without anchor in licensed spectrum Performance advantages Coverage: LTE like, +5-6dB link budget Capacity: LTE link efficiency & MAC Mobility: carrier grade, seamless Robustness: predictable, RLF, SON Capacity gains over Wi-Fi 2X capacity gain over Wi-Fi baseline Higher gains when MulteFire only, especially in dense scenarios Significant capacity advantage outdoors MulteFire summary
- 21. Thank youThank You Formore information, visit us at www.multefire.org