LTE BACKHAUL REQUIREMENTS A REALITY CHECK PETER CROY, SENIOR NETWORK ARCHITECT, AVIAT NETWORKS 1
LTE Cell: Single User Throughput Estimates Data Rate Down/Up [Mbps] vs. Distance from Cell Center Channel Bandwidth Close Medium Far 5Mhz 17 / 5.6 11 / 3.7 5.6 / 1.8 (FDD typical) 10MHz 43 / 14.4 28 / 9.5 14 / 4.8 20MHz 85 / 28 56 / 18 28 / 9.5 IP packet throughput rates vary with RF channel bandwidth and user distance from cell center Majority of handsets in a cell/sector are located within medium & far distance from the cell center (>90% of cell coverage area) High LTE data speeds require exclusive use of radio cell! 2 AVIAT NETWORKS
Estimating LTE Cell Backhaul Capacity Cell backhaul capacity [Mbps] vs. deployment area Channel Bandwidth Dense Urban (close range throughput) Sub-urban (medium range throughput) Typical macro cell tower hosts 3 LTE radio sectors Site backhaul capacity with overbooking factor (OBF) between 3 and 5 Capacity includes 15% dynamic range margin for QoS Rural (medium range throughput) 5Mhz 20 (OBF 3) 13 (OBF 3) 8 (OBF 5) (FDD typical) 10MHz 50 (OBF 3) 33 (OBF 3) 20 (OBF 5) 20MHz 100 (OBF 3) 65 (OBF 3) 40 (OBF5) Figures are already LTE high-end estimates, higher capacities through reducing overbooking factor to 1 from 3 LTE backhaul realistically 10 s, not 100 s of Mbps 3 AVIAT NETWORKS
Backhaul Capacity Trend: 10MHz LTE Channel Capacity [Mbps] 100 75 60 50 40 30 LTE theoretical max. radio throughput (Layer 1) No MIMO, 64QAM 2x2 MIMO, 64QAM LTE single sector backhaul capacity requirement 4x4 MIMO, 64QAM 0 LTE launch Service uptake, New data plans New 2x2 handsets, more sites 4x4 upgrade, Service uptake Time 4 AVIAT NETWORKS
Backhaul Topology Comparison for LTE LTE Backhaul Topology Feature Daisy chain Hub & Spoke Tree/ Tiered Mesh/ Ring Capacity distribution Achieve required network availability Provide LTE cell-to-cell connectivity (X2) Network cost factor Future proof factor Mesh or Ring topology best for LTE backhaul network 5 AVIAT NETWORKS
Backhaul Capacity Example: Ring Architecture Six cell backhaul in dense urban area @50Mbps Multiple site packet capacity not simply sum of cell capacities Network recovers from any single link failure 50Mbps 70Mbps 100Mbps 150Mbps To/from core network 50Mbps 50Mbps 70Mbps Additional ring sites only add incremental capacity! 6 AVIAT NETWORKS
The LTE Hype Cycle YOU ARE HERE! 3G LTE Gartner Hype Cycle, 1995 7 AVIAT NETWORKS
LTE Capacity Conclusions LTE backhaul capacity needs are regularly over-stated Capacity is fixed per site and only determined by base station technology The backhaul limit for a site will likely be ~150 for a 10MHz LTE radio channel Only way to add more network capacity: - Add more cell sites, upgrade to MIMO or increase the LTE channel bandwidth Ring/Mesh topologies are best suited to cope with the high capacity requirements 8 AVIAT NETWORKS
HOW LICENSED MICROWAVE MEETS THE BACKHAUL CAPACITY NEEDS OF LTE STUART LITTLE, DIRECTOR OF MARKETING, AVIAT NETWORKS 9
Uncertainty can lead to bad backhaul choices Backhaul discussion often in terms of hundreds of megabits or even gigabits of capacity Just one in four mobile operators have said that they understood the requirements for LTE backhaul This uncertainty could drive overinvestment for backhaul capacity that is not needed within the foreseeable future 10 AVIAT NETWORKS
LTE Cell-Site Capacity Capacity 1 Gbit/s Maximum Microwave Capacity Room for future capacity growth Cell-site Capacity Curve Maximum Cell-site Capacity (100-200) Time Zone of Capacity Growth Maximum Cell-site Capacity You can t outstrip MW capacity to a cell-site - physics won t allow it! 11 AVIAT NETWORKS
Why pay for capacity you may never need? The total cost of building or leasing fiber to the cellsite far exceeds that of a typical microwave connection Over-building capacity with fiber will waste an enormous amount of network investments 12 AVIAT NETWORKS
The 3 Most Important Backhaul Decision Factors CAPACITY COST RELIABILITY Microwave far exceeds LTE cell site capacity demands Microwave is cheaper than fiber (in nearly all cases) Microwave connected cell sites often have greater uptime than fiber sites Each link needs to be evaluated to understand microwave and fiber costs and capacities OR RISK 13 AVIAT NETWORKS
Microwave Capacity Expansion Options Native Ethernet transport Adaptive Modulation Adaptive Coding Ethernet Frame suppression and compression Capacity-doubling through co-channel operation with XPIC 14 AVIAT NETWORKS
Microwave techniques for high capacity 380 +6% 470 Add Light Coding +24% 550 Add IFG & Preamble Suppression +17% Add MAC Header Compression 311 360 +16% 2xOC3/STM1 Native Ethernet Throughput *Throughput figures are based upon maximum modulation in a 56/80 MHz channel for 64 byte frame sizes. Capacity will be less for smaller channels and/or larger frame sizes. 300 350 400 450 500 550 600 15 AVIAT NETWORKS
Co-Channel link capacity doubling 1100 +100% Add Co-Channel Operation with XPIC 300 400 500 600 700 800 900 1000 1100 1200 16 AVIAT NETWORKS
Getting even more wireless capacity Diverse path network topologies (rings/mesh) Lightly licensed and license free 60-90 GHz Millimeter wave bands Payload compression Higher order modulation schemes >256QAM Multi-carrier operation Multiple-in/Multiple-out (MIMO) techniques 17 AVIAT NETWORKS
Don t let fiber break the bank! Fiber is not the only answer for operators deploying HSPA+ & LTE Operators need to balance realistic capacity expectations with total cost Microwave transport meets the foreseeable capacity needs for mobile backhaul for several years to come 18 AVIAT NETWORKS
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