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Top 10 Factors for an Effective Point-to-Multipoint Network
Top 10 Factors for an Effective Point-to-Multipoint Network
Building a point-to-multipoint radio network is a significant investment for any organization in terms of both the capital and the human resources dedicated to the project. While some considerations might be obvious (such as ensuring you understand the current and future capacity requirements to run your operations), there are other elements which have the potential to create an impact into the future.
Here are our top 10 points to consider if you’re in the market for a point to multipoint network:
1. Invest in Spectrum
As a scarce and valuable resource, spectrum is likely to face greater congestion in years to come. As unlicensed spectrum offers you no control over the priority of data transmission or network availability, investing in licensed spectrum is therefore the first step in protecting your network into the future.
In addition, investing in sub 1GHz channels will offer greater propagation due to less fading from weather impacts and the ability to achieve distance across a large area to maximize coverage. Antenna beamwidth is also very wide in a sub 1GHz channel which means links will continue to operate even if an antenna becomes offset due to wind or ground movement.
2. Bandwidth & IP Performance
Data capacity sits at the top of the list of features which will determine the network provider you choose. Understanding both your current requirements and allowing for growth over the expected life of the network is important. Capacity planning is an integral part of the network design process. However, bandwidth is not just about bit rates per second. Look for innovation around compression rates, high order modulation, MIMO vs SISO and full duplex vs half duplex to ensure your investment in spectrum is optimized through efficient utilization.
IP has been designed for a permanent connectivity world where responses are immediate but traditional SCADA point-to-multipoint systems don’t operate that way. IP traffic can be bandwidth hungry and so achieving excellent IP performance is an important requirement of future-proofed point-to-multipoint networks. Key elements which impact IP performance are high data rates combined with low latency and full duplex communications.
Low latency is another key consideration for mission critical infrastructure. The quicker you can be aware of issues in outlying areas of your network, the better the outcomes for your business and your customers. Industry recommendations are to have latency sitting below 100ms but the potential exists to achieve latency rates as low as 30 ms or even better, based upon both the technology incorporated into the radios utilized and also upon smart network design.
4. Network Integration – ability to support legacy migration
Many existing RTUs are based on serial data from a number of different protocols and standards. In the interests of supporting an easy migration from a legacy system to an IP-based system, your radios will need both IP and Serial interfaces and the ability to support a range of protocols.
5. High tolerance to interference
Particularly important at busy sites, such as those where radios will be co-located with cellular services, the radios utilized must be highly tolerant to interference. In a busy radio environment, features such as bandpass filters to clean noise and a wide dynamic range can go a long way to minimizing interference.
Looking to the future, as more radios get installed adjacent to your original installations, you can expect to be facing greater noise that could create an interruption of service in your mission-critical operations. Therefore, the investment at the outset in radios capable of co-existing with other equipment is an important consideration.
6. Quality of Service
Within a utility organization, there will be mission critical information which must be granted priority during transmission. In a bandwidth-constrained environment, it is essential that bandwidth is not being used to transmit non-essential data when equipment in the network could be in an alarm state. To avoid this scenario, you must either invest in a switch to mark the IP traffic or purchase radios with the ability to set the Quality of Service (QoS) via configurable filters or rules.
Critical Infrastructure Protection is of concern in many countries making the security features of your network a key issue. Look for security features such as:
The ability to isolate Ethernet and serial ports;
Sticky MAC (or persistent MAC learning) where devices connecting into the ethernet port can blocked based on their MAC addresses, and;
Radius Server Support for authentication of users
In a mission-critical situation, reliability is crucial. Key factors will impact the reliability of your system and should be carefully considered:
Quality engineering is the starting point for maintaining reliability – look for manufacturing facilities which meet international standards;
Built-in redundancy at base stations with a 1 plus 1 approach to ensure you stay live even if a radio goes down;
Adaptive Modulation will also increase the reliability of the network as each link in the network can independently maintain its own modulation, irrespective of what might be happening in adjacent links.
9. Engineered solutions
Selecting the product which gives you the capacity, latency and reliability you need is just the first step. There is no substitute for proper RF engineering which includes robust propagation modelling, coverage engineering and site planning to provide you with confidence that you will achieve the coverage required. Allowing you to optimize both spectral-efficiency and network performance as well as minimize interference, smart network design is a crucial (yet at times underrated) component of an efficient, effective point to multipoint network.
Finally, test, test and then, when you’re done testing, test some more. Compare products in the field, put them through their paces under the conditions they will be required operate within and assess the relative performance of different solutions. During this process, you will also get the chance to test the vendor support – another vital consideration when investing in a multi-year, capital expenditure project.