Expect soon to see headline rates for Gigabit LTE, enabled by a combination of standard LTE aggregated by LAA. Commercial service will be launched before the year’s end. But what are the implications for backhaul bandwidth and is our infrastructure ready to take the strain.
An end-to-end solution is essential
A friend of mine moved into an older house and renovated it to a high standard. The bathroom had the latest fittings but it took about 30 minutes to fill the bath. Water pressure was extremely low and using a hose to clean the car resulted in more of a dribble than a full-on power wash.
He traced the problem to a very small diameter pipe that took the main water feed from the street into the house. Upgrading that to a wider “higher bandwidth” pipe solved the problem.
The story highlights that even with the latest equipment onsite, you need every link in the chain to release the full potential of new technology.
Backhaul for wireless could become the weakest link
A similar issue arises with domestic Wi-Fi. Headline peak data throughput of over 1 Gbps are quoted for the latest access points. Even extenders using in-home electrical wiring can achieve 1Gbps. But few residents are able to enjoy a full gigabit internet service delivered to their home. So unless accessing content from a local onsite server or transferring files between home computers, speeds will be heavily throttled by that measure alone.
This is why we’ve seen evidence that average Wi-Fi rates lag behind those of 4G networks, which benefit from widespread deployment of gigabit fibre and microwave backhaul. I’m hearing that 2.5Gbps backhaul isn’t uncommon for the very busiest macrocell sites.
Internet bandwidth for enterprises including hospitality and retail chains is also likely to be more generous than found at many homes. One hotelier told me that many mid-sized US hotels have upgraded from 100Mbps to 200Mbps, but that’s still some way off the full Gbps that modern wireless systems could deliver.
LAA launch expected during 2017
LAA, which aggregates data sent over regular LTE licenced spectrum in parallel with modified LTE at 5GHz promises to achieve 1Gbps. This could be a great boost for those who really want those speeds, downloading large files on demand. Expect to see Gigabit LTE marketed quite strongly in the months ahead.
I don’t believe it will radically speed up the responsiveness of websites because the latency over the radio link will remain the same (it uses the same frame rate). LAA is downlink only, you’ll need to wait for eLAA before similar speed improvements apply when sending data. Video streaming doesn’t really need higher data rates than licenced LTE can already deliver.
What it will provide is much more capacity, so in areas of peak usage you’ll get more bandwidth. That's where performance will be most noticeable.
There will be a cost to it – smartphones which support the feature are likely to be high end ones and thus more expensive. While you may not pay that much more per Gigabyte for the data it consumes (especially on unlimited tariff plans), it won’t be for everyone. But if the very highest traffic users adopt the feature, it should release more capacity for everyone else.
Indoors or Out
Much of the media attention for LAA has been about its high speed capability. I’ve not really seen that much mentioned about the likely deployment use cases. Will it be indoors or outside? Targeted only at a few traffic hotspots or much more widespread? Focussed on laptop/tablets vs smartphones?
One or two clues are appearing. I had thought this would be most likely an indoor play with the 5GHz band being well contained and thus highly reusable within buildings – it doesn’t go through walls very far. However, Kathrein surprised me by launching a new 10 port pole-top antenna designed for 3.5GHz and 5GHz bands in addition to regular cellular spectrum at 1.8 to 2.6GHz. This would suggest some interest in deploying in outdoor urban locations, especially at street level, at least in the US market.
In-building small cell vendors are also launching compatible products. We have already seen Enterprise radio nodes capable of both licenced and unlicenced spectrum, such as SpiderCloud, Huawei Lampsite, Ericsson RadioDot and others. These have an advantage over older DAS systems which typically did not support spectrum above 3GHz and shared the same sector across several floors in a building. Since each LAA transmitter needs to share 5GHz spectrum with any and all Wi-Fi access points in the same sector, this could heavily constrain wide coverage areas and justifies many more independent radio nodes.
In-building backhaul capacity will need to grow to match wireless
Should LAA become a popular choice for in-building Enterprise use, backhaul capacity will have to be addressed so as not to disappoint. Yes of course there are many businesses that have 1Gbps or even 10Gbps links to their premises, but with multiple radio nodes each capable of that bandwidth some careful system dimensioning and customer expectation setting will be required.
For outdoor use, fibre continues to be deployed in substantial volumes. As reported in our last newsletter, Verizon has awarded contracts for supply of 37 million kilometers of fibre (that's around 300 meters per customer), and recently acquired WideOpenNetworks for $275m, a fibre network company in Chicago, to secure backhaul for 500 macrocell and 500 small cell sites.