Bandwidth management has become a key issue for operators and customers alike. The question is just how far can the technology go in improving efficiency, and are we about to reach the limits of what can be done technology-wise?
Maximizing the finite resource of bandwidth and using it efficiently is a key challenge facing end-users, carriers and solutions providers alike.
The scarcity of capacity has become a driving force in the communications business, be it in relation to wireless, copper or fiber optic technologies. Squeezing more information through the same channel without compromising on quality is the ultimate goal of any telecommunications company, as this allows operators to use capacity in increments while keeping cost increases to a minimum.
In wireless communications, the need for companies to optimize bandwidth use has been particularly compelling, as testified by the premium prices commanded by segments of the radio frequency spectrum auctioned the world over. Wireless operators, in fact, are constantly under pressure as bandwidth demand grows to support the popularity of applications such as video and Internet connectivity. Technology innovations that bring efficiency gains are widely seen as the obvious answer to this conundrum.
“All across the wireless industry, not only the satellite industry, we are seeing that increases in demand are driving new technologies as well as new spectrums for commercial use, i.e., white space, re-allocation,” says Michele Scotto, Globecomm’s vice president of network services. “Thus, solution providers will be forced to utilize any and all technologies available to meet their customers’ demands.”
Satellite has long been at the forefront of bandwidth management efforts and the scarcity of satellite capacity has pushed manufacturers to develop new ways to squeeze more bits per kilohertz of radio frequency spectrum.
“In no other telecom sector is bandwidth treated as such a premium resource as it is in the satcoms sector,” says Carlos Placido, senior analyst at Northern Sky Research (NSR). “It is interesting when we read announcements in fiber coding and modulation, using programmable modulation such as BPSK, QPSK and 16QAM, which have been used in satcoms for many years.”
At UltiSat, traditionally we have been dealing with layers three and four of TCP/IP, but the focus now is also on layer seven, the application layer.
— Michael Pollack, UltiSat
How was such a high-level of efficiency in bandwidth optimization reached? Clearly, technical solutions played, and are still playing, a crucial part in attaining this goal. A key, undeniable breakthrough, for example, was reaching near-perfect spectral efficiency at the “physical layer” — the so-called first layer of the Open Systems Interconnection (OSI) model, says Placido. “There are real-world implementations of satellite systems with efficiency within only 0.5 dB of the theoretical limits, the so-called Shannon capacity limit,” he says. “This is primarily driven by use of Low-Density Parity-Check (LDPC) coding in DVB-S2 broadcast/high-speed multi-point applications and in Single Channel Per Carrier (SCPC).”
Experts such as Andrew Lucas, Harris CapRock’s global operations officer, echo Placido’s analysis. “The bit/hertz relationship has become increasingly efficient through the improvement of modulation and coding schemes, along with frequency re-use technologies such as Carrier-in-Carrier and Paired Carrier Multiple Access (PCMA),” says Lucas. “Frequency re-use technologies allow you to receive and transmit on the same frequencies that potentially double the amount of available bandwidth.”
Other solutions allow link availability to be managed dynamically rather than statically configured. This leads to the associated transponder power being released to deliver higher link throughput rather than being held in reserve for rain fade conditions.