Backhaul Communications for Remote Sites

EXECUTIVE SUMMARY

Remote site management systems are designed to enhance situational awareness and ensure operational efficiency of remote sites. However, a reliable means of communicating with these sites must be available, and in our always-connected and on-line world, it may be easy to forget that some areas aren’t easily covered by modern communications channels.

This paper presents different types of channels and means of communicating with remote sites.

1. INTRODUCTION

Remote transmitter sites can benefit greatly from the use of intelligent site management systems. These systems continuously monitor and control site equipment while reporting any problems that happen at the site, thereby ensuring better situational awareness and quicker response times. Finding an available means of communicating with remote sites via an independent channel can sometimes pose a problem, but several options can be available. Some of these options are presented and explained below.

1.1. DIAL-UP

The use of dial-up telephone lines is still possible in regions where this service is available. Your remote site management system must include a dial-up modem, or have it optionally available. If the telephone service is provided via a VoIP (Voice over IP) link, attention must be given to the dial-up modem’s performance over these types of lines.  

If data communications is not reliable over the dial-up connection, you can always fall-back to using DTMF control and vocal-responses from the remote site management system, as long as this functionality is supported in your system.

1.2. WIRED INTERNET

Most urban areas are covered by wired Internet services, but broadband deployments are slowly spreading to suburban and rural areas as installation prices decrease. Delivery can be via DSL lines, cable or optical fiber networks. Ensure your remote site management system can connect directly to this IP link, or at least pass through a site router/switch. If redundancy is important, pay attention to the type of connection used to transport the IP service. For example, a DSL IP connection uses the same line as the dial-up telephone system, so it affords no redundancy in case of line failure.

1.3. Short/medium Range unlicensed Microwave links

If a line-of-sight exists between the remote site and a base site (where wired IP is available), then wireless microwave links can be used quite effectively at ranges of up to 30 km. These systems operate at frequencies of 900, 2400 or 5000 MHz and companies like Ubiquity (https://www.ubnt.com )make a full range of IP-over-microwave products that allow quick, low-cost and easy deployment of IP capability at a site. Since this service is license-free, one disadvantage is that the link can be affected by interference from other license-free systems nearby. Changing antenna polarization can sometimes help in these situations.

1.4. IP OVER cellular

Different generations of cellular technology offer different bandwidths of IP networking, so ensure that your remote site management system can operate over low bandwidth connections like those offered by 3G technologies if that is what is available. LTE (4G) connections should be fine. Wireless routers from companies like Cradlepoint, Sierra Wireless, Advantech and others work very well in these situations. Pricing for IP over cellular data has become surprisingly affordable.

1.5. VHF/UHF Radio Links

In areas where unlicensed microwave links cannot be used, it is also possible to backhaul site data over a VHF or UHF point-to-point radio link. These links use radios from companies like Kenwood, Icom or Motorola that have built-in serial data ports (RS-232).  Maximum data rates in these cases can be as low as 2400 bits/second, so ensure that your remote site management system can operate with this connection speed. Radio licenses will be required for these systems.

1.6. Satellite IP

If a site is very remote and no other land-based technologies are available for network connectivity, then several satellite-based solutions exist today. One of these solutions is the BGAN system operated by Inmarsat (https://www.inmarsat.com/service/bgan/ ). BGAN, which stands for Broadband Global Area Network, offers low, medium and high-speed bidirectional Internet service in all areas of the globe. A coverage map is shown below.

Users purchase a BGAN terminal and then select the appropriate data package from BGAN. Davicom units have been operating over BGAN links for nearly 10 years in all corners of the world.

2. CONCLUSION

Different means of communicating with remote site management systems were presented. Dial-up data, dial-up vocal, Internet, cellular data, unlicensed microwave, VHF/UHF radio, and satellite links were enumerated and explained.

One last point to consider when deciding what type of channel to use is the bandwidth limit of the channel. This bandwidth has to be larger than the bandwidth required by the remote site management system. A remote system with a small, adjustable or selectable bandwidth offers more flexibility for selection of the backhaul channel.  

3. About Davicom

In the mid 1990’s, Davicom started producing and commercializing the first generation of its Remote Monitoring and Control Systems. From the very beginning, these unique systems were designed, developed and maintained with a single objective in mind: to provide the broadcast and telecommunications industries with a low-bandwidth, intelligent and trusted monitoring and control system for their remote transmission sites.

Over the years, new capabilities were added to maintain the product’s position as an industry innovator. From initial VT-100 terminal communications, through the addition of fax & voice capabilities, the units have evolved to the present secure-Internet version with SNMP V3 functionality, iOS/Android App support and smart-functions for adjustable bandwidth communications.. Davicom systems are used worldwide by industry leaders in broadcast, public safety and land mobile radio to help maintain the integrity and operational efficiency of their networks.