It is commonly known that signal interference occurs in the unlicensed bands, especially in areas where the number of users increase rapidly to saturation point. One of the key advantages of using millimeter wave communication technology is the large amount of spectral bandwidth available, especially in the licensed/light-licensed E-band (70/80 GHz). With wide channel bandwidth available, millimeter wave wireless links can achieve capacities as high as 5 Gbps full duplex, which is unlikely to be matched by any lower frequency RF wireless technologies.
MiRO CTO, Marco de Ru, explains that MiRO not only provides technology for use in the unlicensed 60 GHz open band (V-band) frequency spectrum, but additionally in both the licensed and light-licensed 70/80 GHz ICASA-approved millimeter wave E-band spectrum.
The company partnered with manufacturers of very narrow beam width equipment used for point-to-point links, to provide backhaul with high throughput over short to medium distances. A key benefit of the narrow beam millimeter wave links, of typically less than 2°, is the scalability of their deployments. Other wireless technologies often reach their scalability limit due to cross interference before the full potential of such network topologies can be realised.
As radio signals propagate through the atmosphere, they are reduced in intensity by constituents of the atmosphere, such as oxygen. This path-loss effect, usually in the form of absorption or scattering of the radio signals, dictates how much of the transmitted signal actually reaches a receiver and how much of it is lost in the atmosphere. The actual signal loss experienced by a specific millimeter wave link due to atmospheric effects depends directly on the length of the link.
V-band (60 GHz) technology is used for short, sub 1 km links, due to the high levels of oxygen absorption experienced in this range. Interference over shorter distances is therefore minimal and the link is very stable. “Additionally, the 60 GHz millimeter wave technology has such a narrow beam that it won’t interfere with other beams. For example, on one high site one can deploy up to 60 independent radios, offset by a metre. This is not the case with other ISM bands,” says De Ru.
“The law of RF states that the higher frequency, the shorter the distance of deployment should be, but the more throughput you can achieve. However, in the E-band one can successfully establish links of up to 10 km. ICASA has incentivised the market by making licensing more cost-effective as you move to higher frequencies. For example, the cost of using the light-licensed E-band per annum on a 500 MHz link is less than the price of nine burger/chip/drink combos. Similarly, a sliding scale cost is applied to the licensed band,” says De Ru.
“We have found that a number of our existing clients are moving over to millimeter wave technology in the licensed and light-licensed band due to their need for high-capacity backhauls over short to medium distances point-to-point. A MiRO client in Cape Town deployed a link and is achieving 1 Gbps full duplex FDD with less than 2 ms latency,” says De Ru.
MiRO focuses on the supply of carrier grade millimeter wave equipment which has been tried and tested and provides a guaranteed uptime of 99.999%. A planning tool provides users with a guaranteed SLA. When weather is bad, for example in rainy conditions, the MiRO millimeter wave technology has an adaptive modulation algorithm, which allows a drop in modulation without actually dropping the link. Therefore, the communication will still transmit reliably, albeit with slightly less throughput.
“We currently have one of the only radios that can provide 5 Gigabit FDD guaranteed throughput with non-existent noise, allowing multiple radio deployments on one high site. We are also very honoured to have partnered with the first low-cost manufacturer of V-band equipment, increasing the access to high bandwidth equipment in southern Africa. We provide a full consultation service that allows our technical team to assist in determining the most appropriate technology for each specific application,” says De Ru.