Tuesday, 17 November 2015

4.5g from Huawei is LTE- Advanced Pro or we all wait till 5g?

Huawei's Mobile Broadband Forum in Hong Kong was a fun place to attend. While BT and the UK government may think that 10Mbps downstream and 2 Mbps up is plenty of speed for Broadband for the masses, nobody else does it seems, and the mobile world is now gearing up for 1Gbps down and 100Mbps up!!

In fact, the so-called 4.5G non standard, "standard" which has not been ratified even has an official name, and this is relabelled as being "LTE-Advanced Pro". Whatever it’s going to be called, the ability to increase the bandwidth well beyond the 150Mbps of standard 4G comes from three specific technologies, namely carrier aggregation, more reliable advanced modulation, and an increase in the number of antennae.

Carrier aggregation is up and running on EE and Vodafone right now (the networks simply combined), with typically 20MHz of spectrum space from each of two frequencies – say 800MHz and 1800MHz in the case of EE – to provide more bandwidth and up to 300Mbps downstream.

If the two carrier frequencies are contiguous you can get even better performance. The LTE 4g spec would still technically allow lots of carriers to operate, but the cost of licencing the spectrum means that most people are looking to going along the four frequencies path as a sensible limit.

Naturally, merely improving the modulation technique needs far more processing power but Moore's law is our friend here and at least mobile phone carriers don’t need to buy any more spectrum space.

Going from 64-bit to 256-bit QAM (quadrature amplitude modulation), where out-of-phase carriers are modulated, and increasing the rate of modulation improves the throughput no end.

Again, it is the Infrastructure companies that are really keen to sell 256QAM kit into mobile phone operators, and are pushing it hard today.

The final element of the increased performance shtick is the shere magic of MIMO, (multiple-input, multiple-output). This cleverly uses several antennae so that multiple data streams can be transmitted on the same frequency at the same time with clever error correction left to sort out the resultant mess.

In 4.5G LTE-Advanced Pro this is likely to be four or eight instances. For 5G, look to Massive MIMO with 256 or more input and output channels.

Putting all this together, mobile phone operators and infrastructure manufacturers are confident of seeing speeds of 1Gbps as being entirely possible from the technology by 2020.

Huawei and Hong Kong Telecom actually demonstrated a basic prototype system producing 900Mbps at Huawei's Mobile Broadband Forum in Hong Kong last week, with all three technologies running well and a real-world handset running over 200Mbps downstream data rate with just carrier aggregation, and two instances of MIMO.

Putting these very high speeds in the hands of end users begs the question of what the hell will they be used for; yet history has shown that unexpected uses always seem to appear and grow up quickly and sooner or later gradually become the norm. At the forum last week just the two mostly hyped but obvious examples of self-driving cars and augmented reality 3D headsets were much discussed. We'll see how it pans out when 8k video streaming content providers weigh in since that is seen to be their goal!

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