Wireless Backhaul

 

Last year, Accedian’s Ethernet Service Assurance Platform line of products was chosen by FiberTower enable roll-out of its 3G/4G wireless backhaul service. To find out why FiberTower chose Accedian’s platform, and how the deployment worked out, TMCnet caught up with Vijay Lewis, director of national engineering at FiberTower.

 

 

VL: FiberTower’s Ethernet wireless backhaul service for 3G and 4G (WiMAX (News - Alert)/LTE) was rolled out in August 2007, and currently serves WiMAX deployments nationwide in six markets in the U.S., with plans to expand to 12 markets by end of 2008.

 

 

VL: FiberTower is already a leading provider of wireless backhaul services, providing TDM private lines (T1, DS3) to a wide array of mobile operators in the U.S. It has a robust core network in place based on next-generation SONET transport technology combined with licensed digital microwave radio links.

 

To provide the high-performance Ethernet backhaul required for 3G & WiMAX/LTE deployments, FiberTower has “Etherized” its access networks in markets where demand is high. These backhaul offerings are subject to very strict SLAs specifying jitter, latency, committed and excess information rates and availability. This, therefore, requires end-to-end service level assurance (SLA); Ethernet Operations, Administration and Maintenance (OAM); continuous service quality monitoring; and remote test capabilities to maintain efficient network operation and control.

 

FiberTower’s requirements were addressed using Accedian Networks’ Ethernet Service Assurance Platform (ESAP) family of EtherNID (News - Alert) Ethernet demarcation devices.. These devices offer standard’s based OAM, Layer 1-4 loopback testing capabilities, SLA assurance and in-service throughput testing and are capable of monitoring point-to-point, multipoint, and mesh topology networks.

 

 

VL: The combination of the circuit switched performance of a next generation SONET network, combined with edge-to-edge Ethernet service assurance and demarcation provides a carrier-grade Ethernet backhaul network that cannot easily be achieved using other technologies (e.g. MPLS, which normally exhibits less optimal latency and jitter performance, and is more costly to deploy). FiberTower has leveraged deterministic technology such as SONET and Ethernet-over-SONET to implement a simple, yet highly reliable Ethernet transport service, with the distributed nature of Ethernet demarcation units providing service visibility between cell tower and the MSC.

 

FiberTower can now police traffic entering the network, monitor network usage and performance statistics, and publish measured SLA metrics on a Web portal to the wireless service provider — proving the service is meeting strict SLA requirements in real-time. Because Ethernet demarcation units are installed in-line, they can perform complete packet inspection and processing at full wire-speed, allowing traffic to be filtered, mirrored for monitoring or local test set access, regulate bandwidth and assure committed and excess information rates, and provide in-service RFC-2544 service testing to validate bandwidth policies even during periods of peak network usage.

 

All of these functions are performed independently of the access platform being used. These capabilities allow FiberTower to use multiple equipment vendors and technologies to serve cell sites, each being optimized for the particular region or customer’s capacity and service requirements. Installing multiple Ethernet Demarcation units at a cell site allows FiberTower to securely serve and monitor multiple customers’ traffic stemming from a single access platform by providing independent SLA verification and management per customer in a cost-effective manner.

 

 

VL: Ethernet wireless backhaul service is subject to some of the most strict SLAs in telecommunications, including one-way jitter on the order of 1ms, one-way latency on the order of 5ms, minimal packet loss, rapid repair and service recovery times, and committed throughput, all of which are to subject to SLA penalties. Leading WiMAX providers are requesting these parameters be met, and few alternative access vendors’ networks are capable of delivering this level of performance.

 

Converting and/or adapting existing TDM backhaul networks to a packet-centric paradigm in a cost efficient manner requires the low CapEx of Ethernet, but also must keep pace with the performance demands and scalability required to ensure wireline-grade quality of service (QoS) to subscribers. Traditionally, maintaining QoS of Ethernet services has resulted in a steep increase in operations effort, with a high number technician dispatches, lengthy provisioning requirements, onsite troubleshooting and QoS issues that result in OpEx increases quickly washing out the CapEx savings of Ethernet.

 

FiberTower optimized its network by installing EtherNID devices service as demarcation units at all base stations and Mobile Switching Centers (MSCs), allowing continuous monitoring of the service, even in protected 1+1 and multi-homing applications. The Ethernet demarcation service assurance and remote testing approach restores control over Ethernet services, and provides efficient remote operations to address all of the common shortcomings of this technology, while ensuring peak service performance for the end customer (the mobile operator).

 

Each EtherNID at any GE handoff at an MSC can monitor and test the performance of 100 cell-site EVCs homed to it. The EtherNID unit’s proprietary silicon architecture is the only device available that can measure one-way delay and jitter measurements with microsecond resolution, without adding jitter or latency to the service itself, while also providing end-to-end OAM and service assurance functionality. The EtherNIDs provide uniform layer 2 service visibility and management in a distributed fashion, regardless of the network topology or access platform used, which is ideal for wireless backhaul: Fiber Tower’s high performance TDM core network can now serve Ethernet services with the same performance guarantees as that offered for its TDM private line service.

 

 

VL: WiMAX and LTE deployments are currently being undertaken on a national scale by leading service providers in the US, with these services expected to be in full adoption by 2010. These new networks will bring ubiquitous mobile Internet and real-time, packet-based services such as VoIP, mobile multicast video, video conferencing, instant messaging and a variety of media rich presence-based applications to a large subscriber-base of mobile and enterprise users. However, with the increase of data usage and migration of base stations to Ethernet technology, wireless operators will require Ethernet backhaul services.

 

Multiple TDM private lines can be deployed as an alternative to high-capacity Ethernet services, but this is not a cost effective practice considering that by 2012 WiMAX service demands would require the equivalent of 18-20 T1s per cell site - 6-10x the amount currently delivered over 2G/2.5G data networks (2007 survey of mobile operators by Light Reading’s (News - Alert) Unstrung Insider Report).

 

FiberTower’s “Etherized” wireless backhaul services positions them at the forefront of services provided by alternative access vendors. FiberTower now provides high-capacity, SLA-backed Ethernet backhaul to wireless operators by combining the same discrete T1 capacities into a single, multi-purpose, flexible pipe. This is fuelling the cost-effective deployment of 3G and 4G WiMAX and LTE services, allowing mobile operators to develop new revenue streams and positioning FiberTower for long-term growth.

 

 

VL: FiberTower’s Ethernet backhaul services are now available in several markets in the U.S., and performance monitoring results show that the service satisfies the demanding SLAs specified by national wireless operators deploying WiMAX, including one-way latency under 5ms, one-way jitter on the order of 1ms, high availability exceeding 99.99 percent, sub-50ms service recovery, and assured committed throughput. By continuously monitoring these parameters with the Accedian Network’s EtherNID devices, FiberTower can prove to mobile operators that they are meeting and exceeding SLA requirements, and can show prospective customers that their service is truly carrier grade.

 

 

VL: By providing wireline, carrier-grade Ethernet wireless backhaul services, FiberTower allows mobile operators to provide wireline-grade services over emerging 4G wireless networks. This has a profound impact on the future of communications, as it provides the equivalent of wired communications to mobile users as well as fixed-location enterprise customers.

 

The result is a completely new access and communications infrastructure that will establish itself as a significant, competitive alternate to existing wireline networks, without sacrificing service quality and scalability. This will increase competition the communications industry, as well as providing service coverage to rural and less populated regions which currently don’t have access to cost-effective, high-bandwidth communications. Although the original target of such services will be business customers, the potential for residential triple play delivery is well within the capabilities of these networks.

 

From a network provider standpoint, providers such as FiberTower stand to experience significant growth and emergence as a leading service provider, as mobile operators continue to increasingly outsource wireless backhaul to alternative access vendors.