Before the FEDERAL COMMUNICATIONS COMMISSION Washington, DC 20554 In the Matter of ) GN Docket No. 12-354 Amendment of the Commission s Rules with ) Regard to Commercial Operations in the 3550- ) 3650 MHz Band ) To: The Commission COMMENTS OF TARANA WIRELESS Tarana Wireless hereby submits supportive comments in response to the Commission s Notice of Proposed Rulemaking ( NPRM ) in the above-referenced proceeding. 1 Tarana Wireless has pioneered the development of AbsoluteAir, the world s only Universal Backhaul solution that meets mobile carrier requirements for metropolitan small cell backhaul deployments. It provides the flexibility and simplicity of deploying wireless backhaul anywhere small cells are located without compromising capacity or link reliability. Built from the ground up as a carrier class product, this breakthrough innovation combines ubiquitous coverage, unprecedented capacity and scalability, and unparalleled cost effectiveness in both Non-Line-of-Sight (NLoS) and Line-of-Sight (LoS) installations that cannot be met by any other offering. 1 Amendment of the Commission s Rules with Regard to Commercial Operations in the 3550-3650 MHz Band, Notice of Proposed Rulemaking, GN Docket No. 12-354 (rel. December 12, 2012) ( NPRM ).
We applaud the Commissions efforts to make additional spectrum available to address the exponential growth in wireless networks capacity demand. To that end, we respectfully submit the following comments in response to the FCC s NPRM (Amendment of the Commission s Rules with Regard to Commercial Operations in the 3550-3650 MHz Band). I. SMALL CELLS ADDRESS SEPCTRUM CAPACITY NEEDS Tarana Wireless shares the Commission s expectation that increased small cell availability can help address constraints on spectrum capacity. Quite simply, without additional small cell capacity, growing traffic demands will exceed available network capacity. Tarana Wireless concurs with the NPRM s observation that: Demand for wireless broadband capacity is growing much faster than the availability of new spectrum. While the Commission and the President have outlined a path for nearly doubling the amount of available spectrum for fixed and wireless broadband uses, some experts forecast a need for a thousand-fold increase in wireless capacity by 2020. 2 Small cell deployments are already a critical element in the wireless carriers strategy to address capacity needs. However one of the largest operational challenges to small cell deployments is high capacity non-line-of-site wireless backhaul. Generally fiber optic cable is not readily available where outdoor small cells are required. Similarly the trenching of fiber optic cable is generally cost prohibited for small cell 2 See NPRM at 2 2
deployments. Tarana Wireless notes that generally when fiber connections are not available, small cell deployments often require NLoS backhaul. For example, small cells that are located at street level generally are without line-of-sight connectivity, hence NLoS connectivity is required. II. 3.5 GHZ BAND CHARACTERISTICS In light the desirability of NLoS connectivity for small cell deployments, a significant advantage to 3.5 GHz spectrum as a backhaul solution is that it can support NLoS propagation in fixed Point-to-Point (PtP) and Point-to-Multipoint (PtmP) topologies. Tarana Wireless recommends that a holistic approach to small cell deployment anticipate a system comprised of the small cell plus backhaul NLoS radio. Accordingly, a modest amount of the spectrum should be allocated (in the ratio of 1:4, approximately 30 MHz) for wireless backhaul in support of small cells. This provision will accelerate the rapid deployment of the small cell/backhaul system since the solution to backhaul bottleneck is adequately addressed. The backhaul band should be Time Division Duplex (TDD) in order to maximize the efficient use of spectrum (asymmetrical downlink and uplink traffic rates). In order to meet the backhaul capacity requirements of a small cells,), a minimum of 20 to 30MHz of TDD (2-4 channels by 10MHz) spectrum is recommended anticipating that spectrally efficient (>30 bits/sec/hz) methods would be used in this spectrum. Additionally an appropriate guard band should be reserved for wireless small cell backhaul in 3.5GHz band. It is envisioned that spectrum so allocated will be sufficient to service the small cell backhaul requirements for a metropolitan area. 3
To ensure a robust and deterministic backhaul operation, Tarana Wireless suggests that bands should be licensed. Exclusive licensed, flexible-use spectrum bands have proven utilization efficiency, adoption density, and well-established parties to sustainably deploy them. Tarana Wireless notes that highly spectral efficient 3.5 GHz small cell backhaul solutions are available now and can be leveraged to backhaul existing 3G/4G small cells in the cellular bands. Considering that no 3G/4G handset currently support 3.5GHz, it would take many years for handsets to become available in order to commercialize the band for the cellular market. III. TECHNICAL RULE RECOMMENDATIONS Tarana Wireless suggests no changes to the existing 3.65 GHz lightly licensed band to enable current service providers and small companies to continue leveraging that band. Tarana Wireless offers several specific technical rule recommendations: The rules should permit conducted transmitter power of 100 milliwatts/mhz (similar to small cells) into the antenna system at the small cell terminal radio. The backhaul rules should permit advanced Smart Antennas Systems (SAS) to enhance spectrum reuse, to enhance spectral efficiency, and to provide interference mitigation. SAS should allow Multi-User beamforming where the number of beams is N. SAS should allow 2 x 2 MIMO at a minimum In PtMP systems with multiple beams, the rules should limit the transmitted power per beam to 100 milliwatts/mhz(same as Tx power at backhaul terminal radio). Spectral mask should be 43 db + 10log(P) where P is the conducted transmitter power in 4
watts No listen before talk protocol requirement Respectfully submitted, Tarana Wireless By: 2953 Bunker Hill Lane Suite 100 Santa Clara, CA 95054 408-351-4085 February 20, 2013 5