Wireless bridges projects

A very nice gentleman called in representing a Telecoms company. His client has a particular requirement which posed a particular problem for his company. They were not in a position to offer their services for the whole solution as the cost involved in reaching his client with leased lines would be too great, not to mention the hurdles to jump concerning the legalities and time obtaining permission to dig up half the country.

There was however a ray of light offering sanctuary to an otherwise shelved project. A couple of kilometres away was a location that could be used as site A for wireless bridge. Close enough to the primary site that leased lines could be in within the timescales allotted. Deploying the wireless bridge would potentially take a matter of days, therefor would have no impact on the deadline for the project.

Laser 10Gbps

Now that potential locations for the link had been sited the next big question is what is going to be used to achieve this mighty 10Gbps link. There is one technology that is capable of delivering 10Gbps full duplex over a singular link and that is currently Laser technology.

There are many considerations to take on-board when considering bridging with Lasers. Laser bridges can achieve distances anywhere from 20Mtr to 3.5Km which for this requirement would be ample. Adverse atmospheric conditions such as fog, rain, snow and dust could be problematic and the link just happened to be in a part of the UK with a very high percentage of rainfall.

Mounting is also extremely critical as any movement could potentially sever the link. Choosing a solution with auto-tracking functionality would be essential and careful thought would need to be given to redundancy in the event of a failure. It was becoming clear an alternative needed to be considered.

E-Band Microwave

Microwave (Millimetre Wave) technology offers high throughput, not 10Gbps just yet, but there are bridges on the market operating in the lite licensed E-Band 70/80Ghz that will give up to 2Gbps full duplex. Our thoughts are to create multiple links aggregated together to create the 10Gbps required. This would give several benefits over the Laser solution.

Microwave bridges typically feature adaptive modulation. Modulations will dynamically step up and down to counter the effects of the weather. Unlike the Laser this means that the link would potentially never go down in adverse weather conditions. High resiliency would also be had, If one link were to fail only 2Gbps would be lost leaving a still healthy 8Gbps. Redundancy would therefore be not be as critical or negated altogether as a second link failing would be highly unlikely. This would also reduce the overall cost for this part of the project.

Adventures in Wireless

Of course nothing is never that simple, and would boring if it were. There are some challenges to overcome with the Microwave solution. Mounting five links so close together would be challenging not only from the physical installation aspect but there is a question whether there would be enough space available within the spectrum to accommodate five links in such close proximity. This may however not be an issue. Our preferred partner for Microwave solutions, SIAE Micro Electronica, have recently released a 2Gbps E-Band solution named the ALFO80PLUS HD. Later this year there will be an update available which will give XPIC functionality making the 2Gbps a 4Gbps link. Therefore only requiring three links in total.

I love juicy projects such as these. Even though it is still ongoing and still not finalized it gives me a chance to use all of DigitalAir’s resources to overcome the challenges put forward from a project such as this. Of course there will be sleepless nights and inevitable hair loss but no matter what the outcome is I would have learnt a great deal from it.