The explosion of mobile data and the subsequent challenges of connecting a growing number of towers to the mobile core are well known by mobile network operators and wholesalers responsible for mobile backhaul networks. In fact, Infonetics Research forecasts that MNOs will spend a cumulative $39 billion on mobile backhaul equipment between now and 2016. Furthermore, Infonetics (News - Alert) reports that IP/Ethernet equipment makes up more than 90 percent of all mobile backhaul equipment spending, driven by operators looking to reduce mobile data traffic costs, accommodate the 3G mobile broadband data transition, and move to IP as the basic technology of LTE (and WiMAX (News - Alert)).
With mobile backhaul networks representing about one-third of an MNO’s operating costs, it is critical that service providers invest in technology that can sustain current and future network demands. In fact, mobile backhaul requirements will continue to evolve as MNOs accelerate network upgrades to cope with the ever-growing consumption of advanced multimedia services like mobile video, social networking, web browsing, and multimedia messaging. Cisco’s (News - Alert) latest Visual Networking Index indicates that in 2011 a 4G mobile connection generated 28 times more traffic on average than a non-4G connection. Although 4G connections represent only 0.2 percent of mobile connections today, they already account for 6 percent of mobile data traffic.
Given the ever-increasing popularity of smartphones and other intelligent mobile devices, MNOs recognize that revenue growth hinges upon their ability to deliver a growing list of mobile broadband applications and services, which require higher bandwidth and lower latency, to deliver the expected service quality. For example, a video stream viewed on a tablet computer might require HD-quality bandwidth with rapid access to large cached over-the-top content files to achieve the video download consistency required for smooth playback. Putting this issue in perspective, Verizon's online data usage tool calculates that just one hour of 4G high-definition video streaming use will consume 2 gigabytes of bandwidth. While 4G combined with HD may deliver an incomparable viewing experience, usage habits like this place an enormous strain on mobile backhaul networks.
Additionally, a new influx of small cell technologies – ranging from microcells to picocells – is boosting demand for mobile backhaul even further. As mobile carriers increasingly deploy small cells to fill in their remaining coverage gaps and boost the capacity of 3G and 4G technologies in densely populated urban and indoor areas, they will need more backhaul capacity to handle that heavier traffic as well.
Accompanying the rise of mobile data volume has been a dramatic shift in traffic patterns. In stark contrast to the steady and predictable pattern of voice traffic, multimedia traffic is intrinsically bursty and unpredictable. As these multimedia traffic flows are of varying importance, an LTE (News - Alert) network must be engineered to support multiple class-of-service levels that can be assigned to an application based on its priority. For example, based on performance requirements a different CoS, with an accompanying service-level agreement, could be assigned to voice traffic (gold), streaming video (silver), and web access (bronze).
Further complexity arises as MNOs attempt to optimize airtime usage of the shared medium, over which upwards of one hundred or more users must be supported on a single LTE base station (referred to as an eNodeB, or eNB) at any given time.
Smartphones use apps as a user interface to cloud services, but misbehaving or poorly designed apps can sometimes consume much more bandwidth than expected. In addition, smart devices can lock up the allocated communication channel with a status of “in use” by periodically requesting information updates. This commonly occurs when communicating with social networking sites. In the end, additional effort is required to optimize use of the limited spectrum for the wireless link between user devices and the eNB.
In addition to dealing with overall raw capacity increases and new connection-oriented consumption patterns, operators engaged in mobile network upgrades must also consider variables like protocol stack complexity; network resilience attributes; equipment installation and activation velocity; and operations, administration, and maintenance tool requirements. All of these factors point toward Ethernet as the optimal mobile backhaul transport protocol.
The meteoric growth in mobile data traffic parallels a steady decline in the number of cell sites served by a TDM backhaul connection. According to a 2011 Heavy Reading report, less than half of global cell sites will be served by TDM in 2015 – down from 97 percent in 2010. The rationale behind this trend becomes clear when one realizes that the maximum traffic on 4G LTE systems, ranging from 300 to 450mbps in the near term, cannot be carried economically by old TDM and SONET/SDH systems. Unlike predictable voice traffic, 4G data applications generate bursty traffic patterns that require a packet backhaul network to efficiently utilize bandwidth resources. New applications such as VoIP and mobile video also require strict quality-of-service management. These new requirements for the backhaul network are driving a massive overhaul from circuit-switched to packet-based technologies.
According to Infonetics Research (News - Alert), “Carriers everywhere are increasing the bandwidth on their backhaul networks to handle this exploding IP data traffic, and the most efficient, cost-effective way to do that is to transition from TDM to packet IP/Ethernet, which is driving the mobile backhaul equipment market.” Unfortunately, IP/MPLS features an overly complex set of protocols that is better suited to the core where there is a smaller number of nodes with a higher volume of traffic, as opposed to a mobile backhaul network in which there are many more end sites (towers) with less traffic per end site. In contrast, Ethernet’s inherent simplicity and economic advantages render it ideally suited as a mobile backhaul packet transport solution.
Building further on this argument, Ethernet enjoys several important advantages that make it a superior alternative to IP/MPLS for mobile backhaul applications. For example, maintenance activities are greatly simplified due to the fact that IT personnel are already intimately familiar with the Ethernet protocol. In addition, with Ethernet these same IT personnel are not required to master complex WAN protocols.
Network security and control attributes also favor Ethernet over IP. With Ethernet, there is no need to coordinate IP routing tables with the operator(s). Also, superior security is ensured because networking/routing control functions are maintained by the enterprise, which also controls end-to-end networking/routing decisions.
Cost is another important consideration that tips the scales toward Ethernet. In fact, Ethernet can deliver four times the bandwidth and 30 percent savings relative to its MPLS-equivalent when looking at total cost of ownership. This bottom line network cost differential is a key budget consideration, particularly for large multi-site networks.
IP-routed Layer 3 IP/MPLS network solutions add operational complexity and increase the cost to scale and operate the backhaul network. These solutions force backhaul providers to extend complex forwarding paradigms and complex dynamic routing and signaling protocols all the way from the core to the metro, and then into the access domain. The added complexity of IP/MPLS solutions can dramatically increase both capex and opex. The Ethernet layer, on the other hand, provides the right level of connectivity to address the backhaul problem most effectively.
Each protocol-specific forwarding plane has its own associated suite of OAM functionality. This introduces additional complexity when coordinating and managing OAM services across complex protocol stacks. Ethernet services are supported by an extensive standards-based OAM toolkit to monitor the status and performance of the network, systems, and services including tools to isolate and correct connectivity faults, monitor performance variables such as delay, jitter, and packet loss, and conduct performance benchmark tests.
Ethernet-based services also incorporate sophisticated provisioning tools that can reduce the sales-to-installation cycle to immediate plug-and-play speeds, using automated activation of Ethernet switches at the customer site via remote provisioning and self-configuration. Field experience has shown that automation can reduce Ethernet switch installation and configuration times by 75 percent.
Thanks to all of this innovation, carrier Ethernet has proven to be the most technically and operationally proficient solution to address current and future mobile backhaul design flexibility, capacity, latency, resilience, and cost requirements. As a result, the vast majority of MNOs are turning to carrier Ethernet to efficiently carry wireless traffic to its final destination, whether the Internet, a private enterprise network, or government network. In May 2012 the General Services Administration reported that 319 mobile network operators worldwide had committed to LTE deployments or trials – a 60 percent increase over the previous year.
Edited by Brooke Neuman