LTE-A Small Cells 技術 智慧網通系統研究所 馬進國 December 26 th, 2015
Outline LTE HetNet Carrier Aggregation Spectrum Sharing @ 5GHz Cloud RAN MTC @ sub-ghz 2
Mobile Data Era Spectrum Efficiency (SE) More Spectrum More small cells (HetNet HetNet) - SON, (f)eicic, CoMP - CA: carrier aggregation - CRAN - Spectrum sharing 3
LTE HetNet Increase capacity in hot spots with high user demand Fill in areas not covered by the macro network both outdoors and indoors. CRE (Cell Range Extension) 4
(f)eicic (R10, R11) Evolved from ICIC (R8,R9) in frequency domain to eicic in time domain for small cells. Almost Blank Subframes (ABS) includes only control channels and cell-specific reference signals, no user data, and is transmitted with reduced power. When eicic is used, the macro-enb will transmit ABS according to a semi-static pattern during these subframes. UEs at the edge, typically in the CRE region of small cells, can receive DL information, both control and user data. The macro-enb will inform the enb in the small cell about the ABS pattern. R11: further enhanced ICIC (feicic). The focus here is interference handling by the UE through inter-cell interference cancellation for control signals, enabling even further cell range extension. 5 ICIC: inter cell interference coordination
Carrier Aggregation UE CAT (36.306) 6
Spectrum Sharing @ 5GHz UNII 5GHz 頻段具有將近 500MHz 的總頻寬, 而且在傳播損耗的物理特性上也相近於 LTE 系統效能 2.4GHz 與 5GHz 免執照頻段頻寬統計 UNII : Unlicensed National Information Infrastructure 各國 5GHz 免執照頻段規劃與使用現況 Ref : Huawei LTE-U Whitepaper & 電信技術中心 7
Spectrum Sharing Techniques Spectrum WiFi Coexist 3GPP Standard Data Boost Aggregation LTE-U Anchor control channel Duty Cycle (CSAT) R10-R12 SDL (R10) LAA Anchor control channel LBT(Listen before talk) R13 (WI) SDL (R13) UL (R14) RLC level LWA No Anchor 802.11 CSMA-CA R13 WI DL, UL PDCP level MuLTEfire No Anchor Qualcomm? New 8 LAA: licensed assisted access CSAT: Carrier sensing adaptive Transmission LBT: Listen before talk LWA: LTE WiFi Aggregation
LTE-U and LAA LTE-U 採用高通公司提出的 CSAT, 而 LAA 則採用 3GPP 與 IEEE 共識下所發展出的 LBT to ensure fair spectrum sharing. 9 Source: Qualcomm
LAA Release 13 as LAA-LTE (license assisted access) continues to run all control channels in the licensed band and uses the unlicensed bands for additional data plane capacity. Uses the carrier aggregation capability in LTE-Advanced to combine the unlicensed and licensed bands to enable a seamless service offering. The great challenge with this approach involves getting LTE to peacefully coexist with Wi-Fi in the unlicensed bands, but the sharing of spectrum is not in the LTE DNA. Anchored 10
LWA LTE/Wi-Fi Aggregation(LWA) 技術是沿用 R12 Dual Connectivity 的架構, 在 downlink PDCP 協定中, 建立一個 Split DRB(Data Radio Bearer), 由 enb 將資料在 PDCP 做一分流 UE 端再將分流的資料依序重新組合回來, 以達到 data offloading 的效果 Source: Netmanias 11
Cloud RAN (C-RAN) Centralized: support up to 100 cells Fronthaul Network Collaborative: Multicell resource allocation and cooperation Cloud: Open IT platforms Clean: Lower power consumption and OPEX 多細胞多用戶多天線之單一頻率重複使用, 以增加小區總容量 bit/s/hz/ 平方公里
CPRI Vita IEEE 1904.3: Radio over Ethernet Next Generation Front-haul Interface (NGFI) Fronthaul Network (Extended SDR) Radio as a service
Coordinated MIMO Coordinative MIMO v.s. Massive MIMO What is the Role of MIMO in Future Cellular Networks: Massive? Coordinated? mmwave? Robert W. Heath Jr., 2013 14
Airvana OneCell 15
Artemis PCell Cloud RAN architecture,ip fronthaul, interference mitigation technology, DualRAT (LTE and WiFi), x86 based Source: IEEE mag. 2014 Source: http://www.rearden.com/dido/dido_white_paper_110727.pdf 16
LTE MTC Machine Type Communication (MTC) Massive connection, low cost, low power, coverage Source: Nokia 17
Low Cost Source: Nokia
Low Power and Deeper Coverage Source: Nokia
20