Wireless Backhaul: Revolution or Evolution?

There hasn’t been a lot to cheer about over the last year, while the downturn and recession have impacted many facets of the telecom industry. One area that continues to defy the downturn is the growth of high-speed data traffic over the mobile network.

 

In the U.S. alone, 39 percent of the127 million new wireless devices sold in 2009 will be smartphones capable of accessing the Internet. This growth has been taking place over the past several years and will continue going forward.

 

Not surprisingly, once people have the capability to do more with their phones, they want to do more than just phone calls and texting. Data and Internet- based applications; particularly video entertainment, gaming and traffic to multimedia based social networking sites such as Facebook, Twitter, Hulu, etc. have grown dramatically. With the U.S. launch of the Apple iPhone and several other smartphones from Samsung (News - Alert), Blackberry, and Palm, mobile data revenues soared—growing from $13.3 billion in the second half of 2007 to over $15.7 billion by just the first half of 2008. Moreover, deployment of new data multimedia applications is growing rapidly with an overall 2009 –2012 CAGR of 23.5 percent.

 

For mobile operators the revenue side of the equation has had good very news. However, the high volume of traffic has put unprecedented demands on their networks. For example, AT&T (News - Alert), which currently has an exclusive for the Apple iPhone, has received a large amount of publicity over the fact that its existing network has not been able handle requisite demands. Operators around the world will need to upgrade their networks to 3G and 4G technologies such as LTE and/or WiMAX to handle mobile data traffic.

 

One particular area unanimously targeted for upgrading in the move to 4G is the wireless backhaul circuits, which are struggling to meet the mobile data demands on the existing 2G/3G networks. But the question of how mobile operators should upgrade their wireless backhaul still remains to be answered. Are existing technologies used for mobile backhaul sufficient to meet the new requirements? Can carriers add to existing capabilities or do they need to start from scratch?

 

Before we can answer the question on wireless backhaul technology, we must examine how mobile subscribers are changing their mobile habits, which then impact how these changes will transform wireless backhaul networks. Lastly, we will consider what changes will be required to the network itself.

 

 

Voice traffic has been eclipsed by data traffic due to changes in how end users choose to communicate with their cellular phones. Increasingly SMS texting, instant messaging, messaging and “tweeting” (short blogs on Twitter.com), are being used by increasingly more end users (and particularly the teen market) rather than simply choosing to make voice calls.

 

 

Usage of broadband Internet access via mobile devices and wireless PC cards has driven mobile operators to look to new packet-based radio technologies such as 3G upgrades and new 4G (LTE and WiMAX) to improve the access speeds and reach of mobile broadband data services. For example, in the U.S. alone there are approximately 200,000 cell site base stations or Radio Access Nodes (RAN) which are expected to grow to over 300,000-plus sites over the next several years due to more distributed architectures being used for some of the Verizon and AT&T LTE roll-outs.

 

Consequently, with all of these RANs enabled for higher-speed data services, (i.e. 2.5G, 3G upgrades or 4G), the interoffice links or wireless backhaul circuits typically connecting these RAN base station nodes must be upgraded from typically two-to-eight T1s (3-to-12MM) worth of bandwidth to accommodate new 3G/4G or WiMAX capabilities designed to initially deliver 50-150MM transport speeds and ultimately up to 1Gb with newer 4G LTE. Support for end-user download speeds have grown from 256Kbps-1Mbps (2.5G/3G) up to 10Mbps-25Mbps of bandwidth per end subscriber with new WiMAX and 4G LTE technologies. In other words, these new mobile broadband technologies effectively meet or exceed standard fixed wired DSL or cable modem speeds and now are accessible from a mobile device.

 

Who might be deploying these new mobile broadband 4G LTE networks? Recent data from the Global Mobile Suppliers Association (GSA) indicates that up to ten 4G LTE networks are expected to start launching commercial service in 2010 alone. These include: Verizon (U.S.), MetroPCS (U.S.), CenturyTel (U.S.), TeliaSonera (Sweden), TeliaSonera (Norway), NTT (News - Alert) DoCoMo (Japan), KDDI (Japan), Rogers Wireless (Canada), Telus (Canada) and Bell Canada (Canada).

 

 

So how will these new higher speed backhaul connections be deployed? As much of the traffic becomes data- and video-focused content along with some voice, packet-based carrier Ethernet technologies offer the best bet for economical transport for these connections. Recent data from Infonetics, (Jan. 2009 report estimates) projects that nearly 90 percent of the backhaul connections will be based on either wired Ethernet over fiber/copper or microwave connections by 2011 due to the compelling cost differential.

 

Typical PDH private line backhaul circuits are expected to cost approximately $37,044 per backhaul connection versus. $6,887 using Ethernet technology for backhaul circuits. In the U.S., a higher preponderance of wired versus microwave connections is projected mainly due to the lower cost of terrestrial private lines, large geographic regions, and fiber-to-the-home and curb deployments of several of the large incumbent carriers (e.g. AT&T U-Verse and Verizon FiOS deployments).

 

All 2G/3G data upgrades or new 4G LTE or WiMAX footprints will require new base station terminating equipment (BTE) for multi-service aggregation that must be available to handle both 2G/3G migration as well as newer 4G/WiMAX deployment scheme use cases. These new “Swiss army knife” Ethernet mobile backhaul solutions for multi-service aggregation must support not only legacy T1/E1 and SONET /SDH interfaces already deployed today, but also be capable of native Ethernet, PON, and perhaps even microwave to support gigabit and 10 Gigabit connections for newer 4G and WiMAX backhaul scenarios. Further, as mobile traffic becomes increasingly packetized, new timing and synchronization techniques, will need to be employed to ensure clock synchronization can be accommodated for frequency accuracy, phase between base stations, and so time of day stamps can be employed at each base station.

 

Recent IEEE (News - Alert) 1588v2 Precision Time Protocol solutions for time of day and phase have been coupled with new ITU-T G.8261 Synchronous Ethernet standards for frequency distribution combine to address the mobile synchronization problem. In the interim, some carriers are also using a hybrid approach where they leave a T1/E1 circuit for timing and synchronization while packetizing the data into Ethernet transport to ease the migration to a pure packet network. GPS clocking via satellite is also popular (particularly in Japan) as another method for providing appropriate timing and clock synchronization. Moreover, the size and form factor of the multi-service aggregation devices need to be extremely compact and hardened for deployments in remote cell sites.

 

As with cell phones, “small and green is in” for LTE architectures, so look for popular equipment choices to be much smaller and in temperature hardened footprints e.g. 1RU or smaller, yet with the flexibility and modularity to handle various deployment scenarios depending on what type of wireless migration is necessary e.g. 2G/3G/4G LTE/WiMAX. Eventually as next-generation radio equipment comes to market much of the multi-service aggregation technology will likely be integrated directly into the radio devices themselves.

 

Last but certainly not least, new Ethernet mobile backhaul solutions will incorporate real-time SLA and performance-monitoring capabilities ensuring flow-based Quality of Service or (QoS) can be equitably accommodated at the tower itself. Used to address the increasing need for base station traffic prioritization and optimization, QoS and real-time performance monitoring are necessary to effectively manage the unpredictable bandwidth swings occurring during heavy mobile “power user” accessing rich media content such as viral videos, mobile TV, or social networking sites. Operators are being pushed into the unenviable role of allowing all traffic types to pass without selectively policing or dropping customer traffic due to recent Net Neutrality regulations. .

 

Other key problems that must be solved are availability of lower cost 3G/4G LTE/WiMAX chipsets for smaller footprint base stations lower cost MIMO (multiple-in-multiple-out) antennae arrays for increased speed and implementation as well as new multimedia subscriber management gateways to handle different billing policy MOU (minutes of use) types now enabled by the next generation of mobile broadband networks.

 

 

Wireless backhaul really is not a revolutionary thought, but simply an evolution and mandated economical necessity for the existing (predominantly voice centric) cellular networks to migrate to the next phase of (data-centric) wireless mobile broadband networking. With nearly 87.5 percent of the 50 million U.S.-based smartphone owners accessing entertainment from their mobile device, wireless backhaul must evolve to handle the new applications load or there actually might be a revolution.