LOCAL CONNECTIVITY - A bridge to the unconnected
It has now been proven that access to digital communications has a direct and 
measurable impact on economic growth. Yet despite this, Janne Hazell explains, huge numbers of emerging market communities, often located at the very source of the natural resources which fuel the economy, still remain cut off from basic telecommunications. Herein lies the paradox of the Digital Divide; providing communications to drive economic development is, in itself, cost prohibitive. Though several key barriers have been overcome, one still remains, the cost of transmission to, from and between these people
Significant advances in wireless technologies, together with the economies of scale resulting from hugely successful global initiatives such as GSM, have coupled together to provide much of the world's population with cost-effective wireless communications. Competition between equipment suppliers, increased government subsidies and important initiatives, such as the GSM Association's ultra low-cost wireless handset initiative, have all combined to drive down network costs. Mobile network operators (MNOs) and, ultimately the wireless users themselves, have benefited from this wireless industry evolution and we can now experience cost-effective broadband communications. Many MNOs are now focusing on operational overheads, almost exclusively, looking to outsource the operation of their networks and drive down costs further. While the drive to reduce the operational cost of running networks has taken centre stage globally, within emerging markets where arpu is at sub US$10 per month levels, operational overhead costs can often be a bridge too far, leaving communities cut off from basic communications.
While costs vary depending on local factors, one key cost stands out consistently across the world's mobile networks - transmission costs. In particular, transmission costs to and from base stations. Many alternative technologies exist today. Within the reach of the terrestrial telecommunications grid, optical fibre or copper are the dominant technologies and short range microwave links are also common. Cost-effective microwave technology is also dominant for longer distances although the cost of the installation and management of towers has made this an increasingly expensive option. With this the use of satellite as a backhaul technology has accelerated, yet this too brings with it operational cost barriers.
Therefore, the focus has now shifted to the reduction in transmission costs to and from wireless base stations and, with the majority of communications (particularly within emerging markets) being local within the communities themselves, the development of technology to address this local communications requirement.
While the price for network equipment and mobile terminals has fallen sharply since the introduction of global digital mobile networks in 1991, the same deflationary trend has not been visible for transmission costs. Transmission costs have been growing steadily to the point where it is now estimated that anything from 15 to 80 per cent of the total cost of ownership of a BTS relates to backhaul transmission costs. While it is clear that the need for cellular backhaul never will be eliminated, it is also clear that for any area with costly backhaul it is a waste of resources to carry local communications back and forth over the backhaul link. That is to say, that when two subscribers are located in the same area, there is no reason why their intercommunications must travel across the transmission network just to return again to the same area. Industry estimates for such local traffic are as high as 60 to 80 per cent. MNOs are losing significant profit margins because technology has not been introduced to address the wasted cost of local traffic being unnecessarily carried back and forth across the network instead of being switched locally. By switching calls locally, a very significant share of the operational overhead can be avoided, thus making remote rural wireless service more economical for the service providers.
Another cost driver for cellular backhaul is the signaling specifications to which suppliers must adhere. The GSM specification calls for one or more 2mbit/s backhaul links (1.5mbit/s in North America) for any base station depending on capacity. In reality, most remote rural sites only require a fraction of a 2mbit/s link. Any excess capacity is wasted and adds operational overhead to sites that is a financial challenge to start with. A solution to the problem is to change the structure of the backhaul link. The trend is to move from PCM coded TDM backhaul links to IP, as IP lends itself particularly well to handle dynamic link utilization and manipulation. While niche suppliers have introduced stand-alone equipment that converts the backhaul link to IP and removes all unnecessary transmission and silence, Ericsson, the leading telecom supplier, has built-in support for optimizing the cellular backhaul link over IP. The integrated functionality ensures best possible performance, even under severe conditions.
Not only does the high cost of backhaul in remote areas put a strain on the business case for wireless coverage in these areas, the infrastructure and operating expenses must be shared by fewer users than in urban sites. This leads to requirements on lower cost sites and lower cost deployments. As a result of fewer subscribers active on the site, idle load on the backhaul link will also come into play. A 3kbit/s idle load corresponds to a 12-hour voice call every 24 hours, or 20,000 minutes per month. This is the same volume as the expected voice traffic from a 100-subscriber community. From a backhaul perspective, idle load thus doubles the backhaul cost per call.
Based on the above, the ideal solution for small remote communities is a base station with sophisticated link optimisation for long-distance traffic and local connectivity for local calls, which eliminates the idle load when no revenue-generating traffic is ongoing. The base station should be easy to deploy and maintain, require minimal space and work under generous environmental specifications.
We believe that Altobridge's Remote Community solution meets the above criteria. Not only does it deliver cost-effective wireless services to communities with 50 to 500 subscribers in remote or hard to reach areas, it also provides operators with the opportunity to switch locally in any network scenario, e.g. downtown Paris. The technology reduces the backhaul cost to levels below that of sites in the macro network.
The company has addressed the provision of wireless services to communities in the most hard-to-reach areas of the globe. Focusing on the use of legacy satellite technology for backhaul, Altobridge's Split BSC made GSM on commercial jets an attractive proposition for AeroMobile, with Emirates being the first airline to launch the service commercially. That same technology made GSM on merchant ships with as few as 21 crew members a commercially interesting opportunity for Blue Ocean Wireless, with the key to success in both those cases being the ability to minimise backhaul bandwidth utilisation, using existing low bandwidth satellite channels. And now, the same technology is being used to make the delivery of mobile communications to remote communities an interesting proposition for MNOs.
The core of the Remote Community solution is the Split BSC. In simple terms, the part of the BSC handling Radio Resource Management and all other communication with the BTS and the mobiles, has been moved out to the BTS site, while the part handling communication with the MSC/Media Gateway, is kept centrally. This split allows the BSC to manage the BTS and mobiles, without any signaling going back and forth over the backhaul link. Similarly, the MSC ‘sees' all the traffic channels, without having actual contact with them. Once a call is set up, the two halves of the Split BSC establish a connection over the satellite link and the call can be completed.
As the Split BSC resides on either side of the satellite backhaul link, it is in full control of how and what is transferred over the link. In addition to just optimising the payload by removing padding and silent frames, the Split BSC transcodes the signal. The transcoded signal requires 5-8 kbit/s per active voice channel, compared to 17-25 kbit/s required by competing solutions. In many areas of the world, the difference represents 4-5 US cents per minute, effectively the entire profit margin. Add to that the idle load and it becomes clear that the Remote Community solution is ideal for addressing small remote communities, profitably.
To further improve both business case and user experience the Remote Community includes the Local Connectivity solution, which handles all local calls locally. With 50 per cent local calls, the backhaul cost drops a further 50 per cent. The company's patented Local Connectivity functionality is unique in that call control, charging, supplementary service management and O&M remains in the control of the MSC. The transparency ensures that the investment in optimising the central core network and service layer is protected and no expensive and complex distributed architecture is introduced. As Local Connectivity eliminates double satellite hops for local calls, users will also experience improved network quality. This usually leads to longer call holding times.
For larger subscriber groups beyond the populations addressed by the Remote Community solution, the Local Connectivity feature is also available through Ericsson on their entire range of GSM base stations (see boxed text).
Using such a solution, operators have an attractive opportunity to provide communication to an untapped market - remote communities - that was previously considered too small or too costly to address. Universal service obligation now becomes a profit opportunity rather than a regulatory liability, and first movers will be able to lock in new subscriber groups if they recognize the technology now exists to do so.
The digital divide has shrunk considerably!
Janne Hazell is Altobridge General Manager, Remote Community Communications
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