Another challenge to successful satellite LTE backhaul comes via atmospheric conditions. Rain and snow can cause interference and interrupt signals, causing degradation in connection quality or even complete loss of a satellite signal.

Choosing the Proper Satellite Technology

When looking at satellite technology that is compatible with LTE connectivity, MNOs should focus on K-spectrum bands. The K-band’s high frequency physics provide 10 times more bandwidth than other satellite technologies and can reduce capacity and transmission costs because of this efficiency. Moreover, because LTE provides all-packet architecture, it meshes well with K-band technology. Packets can be adjusted to drive transmission efficiency, extremely low latency and high performance as a way to compensate for the natural limitations of transmitting data to and from satellites in geosynchronous orbit. This occurs by using techniques, commonly referred to as acceleration applications, that can be made to move easily with satellite backhaul.

Ka-band satellites, which transmit on the top part of the K spectrum, are well-established and proven technologies for cellular backhaul. Ka-band bandwidth is plentiful, and its higher frequency creates less chance of spectrum interference. Once considered too slow for LTE connectivity, the newer Ka-band satellites provide 10 times the throughput that they did just two years ago. Shared services, particularly in Ka-band systems, can allow the cost per gigabyte to be competitive with current rates from carriers.

Ku-band satellites operate on the lower part of the K band spectrum and have more bandwidth than is available with Ka-band. This capacity allows even greater volumes of traffic to be transmitted at higher connectivity speeds and better supports higher bandwidth applications—all-important elements of satisfactory LTE connectivity.

Of course, all of this comes with a price for the MNO. Satellite backhaul is not inexpensive in any case, but arguments can be made for choosing either Ka-band or Ku-band, depending on the application and the allowable budget. Generally, Ka-band can offer a lower entry cost for LTE wireless backhaul. Ka-band ground base equipment—ground terminals and base stations—is costlier than its Ku-band counterparts. Ka-band transmissions normally are less expensive, as well.

Finally, MNOs evaluating satellite backhaul cannot overlook the propensity of weather-related interference. Although Ku-band is better at supporting higher bandwidth applications, it also is more susceptible to rain fade than Ka-band. This problem can be overcome by increasing transmitting power, but the result is increased costs.

Understanding LTE, Satellite Backhaul and M2M

As machine-to-machine (M2M) communication plays an increasingly key role in commerce and individuals’ everyday lives, reliable connectivity will be paramount to its success. For the most part, M2M applications such as logistical tracking and remote monitoring do not require high bandwidth and real-time reporting, so they work well on 2G and 3G networks where satellite backhaul is less expensive.  However, as M2M evolves to include more content-rich video applications and large operators phase out legacy networks, M2M connectivity providers will need to shift to LTE networks. Again, in most cases, the latency and weather disruptions that can sometimes afflict satellite backhaul will be insignificant as users have more tolerance for less immediacy with most M2M functions.

Roadmap Options for Meeting LTE Connectivity Goals

Integrating satellite backhaul as a way to provide or expand LTE reach can be approached in a number of ways, depending on each MNO’s goals and challenges:

• An operator that needs to meet service obligations in low-density, geographically-accessible markets without reducing profitability can deploy satellite-equipped base stations and use satellite backhaul for cost-effective connection to the base station controller. Then, when rising revenue and traffic volume meet investment requirements, the satellite backhaul can be replaced with optical fiber.
• An operator that is looking to minimize the capital cost of launching a new network can deploy a satellite-based network with hosted switching, deferring the capital costs of terrestrial backhaul and carrier-class switches until justified by revenue growth.
• An operator that wants to avoid or delay the high cost of replacing legacy base stations and switch blocks but still wants to take advantage of advanced revenue-generating services made possible by LTE can deploy an overlay network. They can do this by linking satellite backhaul to a dedicated switch, integrated into its own BSS and OSS, which provides the services.

Clearly, optimal LTE connectivity happens when communications are sent via fiber. However, if this simply is not possible due to geophysical or financial limitations, satellite backhaul provides a viable and often affordable alternative that can open the door to network growth and new revenue opportunities.