Mobile industry enthusiasts have been warned at length about the proliferation of LTE devices forcing backhaul to become markedly different than it is today, especially in terms of capacity delivery. Other challenges for the service provider include rising cost of capital, increasing network complexity and the ability to gracefully accommodate future technology shifts such as SDN, NFV and SON—Software-Defined Networking, Network Function Virtualization, Self-Optimizing Networks. A Layer 3 IP/MPLS topology has addressed many of these goals so far in the aggregation and at the service provider edge of the network. MPLS, Multiprotocol Label Switching, in particular, has offered converged service delivery, fast failure recovery and advanced Quality of Service.
So what’s next? The fundamental transformation needed next is at the cell site, which is evolving from its basic role of housing a base station to the new reality of enhanced service delivery hub. Why is this important? It’s simple: MPLS allows operators to offer enhanced revenue-generating services while simultaneously enriching the consumer experience and feeding an entire mobile ecosystem.
Battling rising costs by monetizing new services
The day of reckoning for operators is predicted to come with the confluence of rising costs and shrinking ARPUs, leading to unsustainable losses. Additional revenue sources are the key to profitability, provided they could be enabled swiftly and seamlessly. Fortunately, MPLS is available as a steppingstone to new services. As high capacity and scale infiltrate the end-to-end network, the traditional macro site can be considered the new point-of-presence for revenue generation. MPLS-enabled services include Layer 3 VPNs (L3VPN), Layer 2 VPNs (L2VPN) and Virtual Private LAN Service (VPLS). L3 VPNs are attractive to customers (e.g. enterprises, government) who want to leverage the service provider’s technical expertise to ensure efficient site-to-site routing. L2 VPNs are attractive to customers who want complete control of their own routing. Finally, VPLS makes the service provider’s network look like a single Ethernet switch from the customer’s viewpoint, effectively making their WAN look just like their local campus.
For the mobile provider, the backhaul topology changes have already started to take shape, with Small Cell as one example of how cell sites will evolve, essentially becoming aggregation nodes as small cells (i.e., cloud RAN, IP, wifi) are added to network. This leads to a tangled web of complexity in a modern, heterogeneous network.
Technology flexibility to alleviate network complexity
To date, MPLS-enabled routers are the only proven solution to cost effectively converge multi-service interfaces onto a single low cost IP transport platform. The multitude of devices at the cell site includes legacy interfaces such as TDM, ATM and even Frame Relay. With its ability to decouple protocols from their physical transport medium, MPLS provides a single converged transport solution for all access technologies. As MPLS is generally deployed in core networks, adding it in the access is just an extension of the existing network transport architecture.
Beyond multiprotocol capability, the current hype of SDN, NFV and SON ushers in new challenges that are intended to optimize, virtualize and control the network—albeit with a significant operational learning curve. The capabilities of MPLS align with each of these goals, when they come. MPLS enables vendors to offer solutions that simplify management and protocols, provides fast adaptation for new services and eases the burden on personnel for general network turnup and maintenance—including tasks such as new base station provisioning, debugging, troubleshooting and performance monitoring
Benefits of IP/MPLS at the cell site
The benefits of IP/MPLS at the cell site are numerous, especially for LTE and LTE-A deployments. When compared to flat Carrier Ethernet networks, routers can scale to vast numbers of nodes. MPLS enables a scalable X2 network design. (X2 is the LTE interface used for Handover, Load Management, Mobility Optimization, Network Optimization and LTE-Advanced CoMP eNodeB coordination.) With eNodeBs on different subnets, routing is required between Layer 2 domains for a complete X2 solution.
MPLS-Traffic Engineering (MPLS-TE) provides operators with capability to steer traffic across backhaul networks, thereby increasing overall capacity and lowering latency for latency sensitive traffic flows—this is an important requirement for LTE-Advanced. MPLS-TE can increase backhaul capacity by 50 percent when compared to L2 networks.
How to Add IP/MPLS to the cell site
Introduction of IP/MPLS into the access network can be easily accomplished with networking platforms such as the Aviat CTR microwave router. The CTR 8540 is the industry’s first purpose-built microwave router—a unique concept that merges the functionality of an indoor microwave radio and a cell site router into an integrated solution, simplifying IP/MPLS deployments and creating a better performing network. The Aviat CTR helps operators avoid the investment of expensive standalone routers, translating to overall fewer boxes to buy, deploy and maintain. See more information on Aviat’s IP/MPLS solutions.
Senior Manager of Marketing
As the telecom community searches for reasons why Small Cell architectures have not yet launched en masse, “experts” are quick to suggest that lack of backhaul technology as the key perpetrator.
As I wrote in a 2013 article, starting with wireless microwave communications (6-42GHz frequency range), solutions for backhaul both large and small are available and effective today for mobile operators.
This is the second in a series that highlights technology available to enable immediate deployment of small cell backhaul. This segment focuses on the convenience of using wireless E-band as a complement to microwave for small cell backhaul, while bringing to light some of the true obstacles to small cell adoption.
E-band is a part of the electromagnetic frequency spectrum in the millimeter range between 71-76 GHz and 81-86 GHz. In recent years, there has been more interest in this frequency band, because traditional microwave (6-40 GHz) bands are now very congested in parts of the world, and that with the densification of mobile networks due to the introduction of 3G/HSPA and 4G/LTE, link distances between cell sites are shrinking in urban areas.
The surge in interest in a new network of outdoor small cells is driving a new approach toward cost-effective wireless solutions for backhaul. E-band offers a large swath of available spectrum with more than 10 GHz at stake—it represents more bandwidth than all the combined open frequency bands below 40 GHz.
What is needed is an all-outdoor, packet millimeterwave radio, offering a rich set of features, expressly built to support mobile (macro and small) backhaul by:
As the world becomes increasingly urbanized—for the first time ever, more than 50 percent of the world’s population lives in dense urban areas—it is also the place where we communicate the most and networks are most stressed to keep up. Small cell designs offer a convenient method to densify networks.
However, my prediction is that in the near to medium term, deployments will be surgical—to plug gaps where coverage is poor and to fill hot-spots where incremental capacity is needed. It is important to note that outdoor, public access small cells will coexist and in some ways compete with other densification solutions, including DAS, wi-fi, and additional macro cell builds. Small cells may indeed need to be backhauled from light poles and building sides, but ultimately they need to go where they need to go, while serving the primary goal of not-spot and hot-spot filler.
The more pressing obstacles for outdoor small cells include the method operators use to assess the business case and solve the construction and site acquisition challenges borne by the paradigm shift. The expectation is that the ecosystem will produce a solution that makes small cells easier and cheaper to deploy than macro cells. The problem with that thinking is the economics of it all. The business case will continue to struggle to prove out vs. macro cell, as scalability and network dimensioning quickly come at odds with requirements for unbridled capacity, high reliability and network intelligence.
Operators think they may be vying for a diminutive device supporting multi-generational, multi-band, multi-media and multi-OSI-layers, but that utopian requirement breeds complex challenges in permitting, site acquisition, interference, costs, and so on—all items recently in the pick-list of a flash poll by Light Reading. I maintain that we are not just over-thinking, but over-expecting the benefits of a pure-play small cell rollout. We might all be better off following the “K-I-S-S” principle for the foreseeable future, which might produce this guidance:
So here’s to Keeping it Small and Simple!
Senior Manager of Marketing
The Case for Small Cell Backhaul
As the search for frequency bands with suitable capacity for small-cell backhaul continues, frequency bands above 50GHz start to appear attractive because they offer both high-bandwidth availability and short range owing to their inherent propagation characteristics. The white paper available at the bottom of this blog examines spectrum in the 57-64GHz range to see whether it can be of use for small cell backhaul.
In many countries, the frequency range 57-66GHz is split into a number of discrete bands with differing requirements and conditions of use and/or licensing. These differences will be highlighted where applicable.
From a global point of view, the use of this spectrum by Fixed Services (FS) is being addressed by the ITU-R in its draft report on Fixed Service use trends in WP5C, which is currently under development and states:
57 GHz to 64 GHz
The radio-frequency channel and block arrangements of these bands for FS are defined in Recommendation ITU-R F.1497.
In 2011, around 700 links were in use in this band in a few administrations. The majority of the links are used for fixed and mobile infrastructure.
The air absorption around 60 GHz is over 10 dB/km. This condition restricts the hop length; on the other hand, the spectrum reuse efficiency is high. This feature makes the band suitable for small cell mobile backhaul.
Clearly, a global reported usage of 700 links would suggest a great deal of underutilization, although with unlicensed use in many countries it is difficult to know whether these figures are accurate or not. Regardless, there are reasons as to why this could be the case, while noting that the ITU-R believes this band has potential for small cell backhaul.
One factor is that this spectrum is not allocated solely to the Fixed Service. In fact, in many countries the Fixed Services have no access to this spectrum at all. A more detailed country-by-country breakdown follows. Please sign up below to receive the entire white paper.[contact-form-7 404 "Not Found"]
Small cells get all the press! As LTE rolls out in networks on every continent except Antarctica, small cells are grabbing headlines in technology trades and geek fan-boy blogs across the Internet. They’ll be needed sooner or later to provide LTE access in all those places around corners of buildings on business campuses, in urban parks surrounded by concrete canyons and other inaccessible locations. But little or only passing thought is paid to the ways in which small cell traffic will be aggregated back to the main network.
However, in a new FierceWireless ebook, microwave backhaul is pointed out as one of the critical strategies to provide throughput for all the small cell traffic to come. Microwave was here before small cell. And it’s such a good fit for small cell, if it had not already existed, we’d have to invent it now! Our director of product marketing, Stuart Little, tells FierceWireless that microwave meets the capacity needs of LTE backhaul. And Fierce adds modern microwave technology is changing the perceptions of its use for small cell backhaul.
Neither sleet nor rain nor changing K factors at night will stop microwave from small cell service. Specifically, Little tells Fierce that rain has little to no effect on microwave at the lower frequencies, and where it does have some effect in the higher bands, different technical techniques can help mitigate it. To find out more about small cell microwave backhaul, we recommend any of the Aviat blogs and related articles below. Or just read the FierceWireless ebook.
Mobile backhaul has become one of hottest and most contentious subjects in telecommunications ever since LTE cellular phone technology started to ramp up. One much overlooked aspect of deploying LTE lies not in the capacity required to backhaul cell site traffic but the effort required to build out the required sites. It is really about site surveys, frequency coordination, engineering, planning and installation. Aviat Networks’ chief technology officer (CTO), Paul Kennard, addressed this dichotomy and others related to LTE in his presentation to the IEEE’s Communications Society.
Although, Paul did have plenty to present regarding capacity. For example, with proper use of rings, overbooking, QoS, XPIC and other techniques and technologies, microwave backhaul can provide 400 Mbps-plus throughput. Compare this to the realistic throughput demands of a typical LTE site that max out at about 100 Mbps.
He also delved into the emerging backhaul category for Small Cells—designed to supplement traditional cellular infrastructure. The fact is that traditional techniques of deploying cellular macrocell basestations will be insufficient to provide broad enough coverage for this LTE wireless technology. To augment macrocell coverage for LTE mobile telecommunications providers have been investigating, trialing and, in some cases, deploying one or more of several small cell technologies (e.g., picocell, microcell, femtocell). Consequently, new methods will be needed to backhaul traffic from Small Cell sites.
Fiber backhaul may not be available at all small cell sites and when it is it could be very expensive to trench long distances. Regular line-of-sight (LOS) microwave with its parabolic dishes could prove aesthetically unsuitable for many Small Cell locations and/or difficult to install. Non-line-of-sight (NLOS) microwave and millimeter-wave point-to-point and point-to-multi-point wireless may have their applications, but their latency of 5-10 ms may be too much for real-time applications and voice—not to mention licensed spectrum is costly and unlicensed spectrum is very risky due to interference issues.