Ethernet Backhaul for 4G: Successes and Challenges Presented by Dave Jones SVP Network Services, FiberTower

Outline 1.FiberTower Overview 2.4G Backhaul Requirements 3.Bandwidth Requirements by Cell Type 4.Case Study: Fiber vs. Microwave 5.Successes to Date 6.Challenges to Be Met

FiberTower Overview A 2010 fastest growing technology company in North America - #118 on the Deloitte 2010 Technology Fast 500 A 2010 fastest growing technology company in North America - #118 on the Deloitte 2010 Technology Fast 500 Facilities based hybrid fiber/microwave backhaul provider delivering the critical link between wireless consumer access and the core network Long track record: Delivering service quality & operational efficiencies with backhaul & premise access solutions since 2003 Operating networks in 13 major markets with extensive, nationwide spectrum footprint in the 24 GHz & 39 GHz bands Utilizing unique and optimal mix of fixed wireless and fiber technologies to provide highly scalable, cost effective solutions for advanced wireless networks FiberTower, a leading backhaul services provider, increasing the overall quality of wireless networks Products & Services SONET: nxT1, DS-3, OC-n Ethernet: 5mb to 1Gig Wavelengths: Inter & Intra Metro TDM to Ethernet Migration Carrier Class, Highly Scalable

4G Backhaul Requirements Carriers require long-term backhaul solutions that can scale with their business needs Timeframe for implementation is now Challenge – achieving the Three Cs – Coverage – Cost – Capacity Key Requirements Capacity Coverage Cost Quality Ethernet support Clear path to 300+ Mb/s per site Solution for all sites in a market Rapidly declining cost structure ($/Mb/s) TDM-like quality (availability, performance specs) Technical requirements + ability to support a graceful migration from TDM Ethernet Variations Service configurations E-Line (EPL, EVPL) E-LAN Various VLAN tagging schemes Classes of Service CBR VBR-RT VBR-NRT Best Effort Handoff Types Cell site 100baseT, GigE Electrical or optical MSC GigE, 10GigE, SONET Protected, Un-protected Carrier-Grade Ethernet transport is not a commodity!

Bandwidth Requirements by Cell Type Site TypeRadius4G BandwidthBackhaul Technology macro2-10 miles MbpsFiber or microwave (carrier class) micro0.2-2 miles MbpsFiber or microwave (carrier class) pico feet20-50 MbpsFiber or microwave (carrier class) femto<300 feet5-10 MbpsCable or xDSL (user provided, best-effort) Indoor Coverage Outdoor Coverage Operator-deployed User-deployed Deployment of picocells and femtocells will explode as 4G networks are rolled-out in order to provide the required in-building coverage and capacity, and will present new backhaul challenges.

Case Study: Fiber vs. Microwave Objective: To evaluate the impact of a hybrid fiber-microwave network architecture in a Tier 1 market using real-world data Input Data and Assumptions: Major wireless carrier site list Major, high-density fiber network Licensed microwave radio equipment (11-24 GHz) Evaluate % of sites reachable by: Lateral build from fiber backbone (0.5 and 1 mile range) 1st hop microwave from fiber-fed sites (5 mile radius) 2nd hop microwave from fiber-fed sites (5 mile radius)

Case Study: Conclusions Depending on the fiber lateral distance that can be economically justified, 39 to 60% of sites can be served by fiber (ideal case) By leveraging microwave radios to create a hybrid architecture, ~95% of sites can be reached In Tier 2 / Tier 3 markets, where sites are more widely distributed and fiber routes are less dense, the % of sites economically reachable with fiber is much lower and the relative impact of microwave will be greater

Hybrid Fiber-Microwave Architecture Legend MSC = Mobile Switching Center FEP = Fiber Exchange Point RF = Radio Frequency

Successes to Date Ethernet backhaul deployment is progressing rapidly in Tier 1 markets for most major carriers Demand for backhaul capacity (Mbps per cell site) is accelerating New backhaul providers - cable MSOs and alternative access providers – are playing significant role Most wireless base stations are now Ethernet backhaul-ready

Challenges to Be Met Many sites in Tier 1 markets are proving difficult to reach with fiber Tier 2 and Tier 3 markets will be more challenging due to dearth of fiber options and lower cell site densities, especially in rural areas Most carriers have unique technical requirements, which continue to evolve based on results of initial deployments Bandwidth requirements and user data traffic characteristics need to be better understood in order to optimize backhaul network performance and economics Picocell backhaul will require new, low-cost approaches to address deployment and line-of-sight challenges