The Problem with C-RAN is Fronthaul

Southeast USA at night: All these urban areas will need a small cell backhaul solution for LTE at some point. Will it be "fronthaul?"

Southeast USA at night: All these urban areas will need a small cell backhaul solution for LTE at some point. Will it be “fronthaul?” Photo credit: NASA’s Marshall Space Flight Center / Foter.com / CC BY-NC

With the mobile telecommunications space facing an onslaught of data-hungry subscribers and their migration to LTE, operators have embarked on a quest to pack even more service in smaller and smaller service areas. The frontier of these smaller service areas have come to be characterized as small cells. The issue is getting communications into and out of these small service areas. Capacity, coverage and interference all need to be addressed. Some have proposed serving small cells via Centralized Radio Access Networks (C-RAN). To implement a C-RAN, one of the requirements is a newer concept that has come to be termed “fronthaul.”

In a June 2013 meeting of the Telecom Council, Aviat Networks’ chief technology officer, Paul Kennard, took on fronthaul and the challenges it presents for LTE, small cell and C-RAN. In his presentation, he weighed the advantages and obstacles of fronthaul. While the chief advantage of distributing Remote Radio Heads (RRH) around the cell can help alleviate coverage, capacity and interference concerns, it is not easy to reach these RRH locations with fiber in the mostly urban areas where this deployment scenario will be needed most. This is especially true of non-traditional implementation of small cells on light standards, signposts and other non-tower infrastructure collectively known as “street furniture.” Wireless backhaul solutions will continue to be necessary in the grand scheme of things.

More is available on fronthaul in the Telecom Council presentation below as is in an associated webinar.

5.8GHz FCC Rule Change: Good or Bad?

In the United States, the fixed service for wireless communications usually operates in bands licensed either on a link-by-link basis or by block allocation. So why is the 5.8GHz ISM band so important and why should the industry be concerned about current FCC proposals to change the rules of operation in this band.

Many operators use this band because they can install and operate a link in a very short period—much quicker than the usual route of prior coordination and license application that is required in other bands. There are numerous reasons why this approach is attractive, even if it is difficult to guarantee Quality of Service (QoS) in ISM. A common use of this approach sees the operator set up a link in the 5.8GHz band to get the link up and running while in parallel it goes through the coordination process for the same link in the L6GHz band. Then when that license is granted, the operator will move the link to the L6GHz band. This has the advantage that the same antenna may be reused and sometimes the same radio with just a filter change. Another use of the 5.8GHz band for fixed service links is in support of disaster relief efforts where because there is no need for prior coordination that means vital communications links can be up and running very quickly.

Under the current FCC Part 15 rules, equipment can be certified using section 15.247 whereby the above scenarios are attractive to operators as they mimic the conditions that can be found in the L6GHz band. However, the FCC has issued a notice of proposed rulemaking, NPRM, which will change this by requiring a reduction in conducted output power of 1dB for every dB of antenna gain over 23dBi for Part 15.247 point-to-point links. At present, the conducted power at the antenna port in this frequency range is limited to 1 watt, but there is no penalty applied to the conducted power in relation to higher gain antennas on point-to-point links. Should this proposal by finalized then this would reduce the effective range of point-to-point links in this band and would so change the dynamics that the ability to deploy a link in the 5.8GHz band and then “upgrade” to the L6GHz band at a later date would no longer be a feasible option. We would encourage all readers, especially those using the 5.8GHz band to file a comment with the FCC regarding Proceeding 13-49 that this particular change would be detrimental to many fixed link operators, as well as those who rely on this band for fast deployment during disaster recovery.

For more information on this proceeding, email Aole Wilkins at the Office of Engineering and Technology.

Ian Marshall
Regulatory Manager
Aviat Networks

Public Safety Broadband Stakeholders Have to Decide

PSCR-hosted-the-Public-Safety-Broadband-Stakeholder-Conference-June-4-6-2013-in-Westminster-ColoradoIn the effort to build out the nationwide Public Safety Broadband Network, stakeholders are making themselves heard. They were heard at the Public Safety Broadband Stakeholder Conference held last week, June 4-6, 2013, outside of Denver, Colo., hosted by the Public Safety Communications Research lab. It brought to the surface the many competing agendas local public safety network operators, the First Responder Network Authority (FirstNet), wired and wireless vendors and even mobile app developers contend with.

Aviat Networks had a chance to sit down with Tammy Parker, editor of FierceBroadbandWireless, during the conference to discuss some of these issues, such as the debate on the effectiveness of fiber optic technology in backhauling public safety networks. The fact is that microwave indeed will be a key element in the design and implementation of the FirstNet mission-critical network. And fiber does not provide the reliability and survivability needed. In the commercial mobile telecom space, the poor survivability of fiber is tolerated, but when it comes down to crunch time when lives are on the line, public safety operators will take microwave over leased fiber.

Randy Jenkins, Aviat director of business development, expanded on this vital decision for public safety operators to make between microwave and fiber. “As a vendor vested in the public safety community for more than 50 years, Aviat understands its responsibility to find innovative ways of offering microwave solutions that can save CAPEX and OPEX in support of the biggest challenge FirstNet is addressing—not enough money. Aviat is bringing backhaul innovation to this program.”

The bottom line is that backhaul is always the bottleneck in any network planning. In that case, it’s important for public safety operators to address that aspect first, according to Tony Ljubicich, Aviat’s vice president of sales and services.

If you would like to hear more about how Aviat Networks is making microwave backhaul the best choice for FirstNet-ready public safety, leave your contact information and reference the upcoming webinar on public safety broadband backhaul for a major statewide network. We’ll let you know when it’s scheduled.