Are 5G advanced Antenna Techniques the primary way to maximise 5G value?
WHERE IS THE OVERALL 5G VALUE AND WHO REALISES IT?
There are two obvious answers in terms of the main generators of overall 5G value. One is that 5G facilitates cost-effective additional capacity through access to new spectrum, efficient use of that spectrum and ease of base-station deployment critical to realising the full potential of that new spectrum.
Secondly, it allows new use cases to be supported encouraging connected innovation and new deployment scenarios. Looking at cost-effective deployment of additional capacity, though - this is a way of reducing, or at least constraining, costs for their existing business model, whether or not operators are able to realise the newer revenues associated with new 5G use cases.
WHY ARE ANTENNA ARRAYS SO IMPORTANT TO 5G DEPLOYMENT?
Fundamentally, we are talking about energy in the form of oscillating electrical and magnetic fields. The fields can be configured or optimised in a variety of different ways, with varying degrees of mathematical complexity, in order to focus the energy in a certain direction (beams) or around a certain point in space (bubble).
Of course, focusing the energy will increase the signal strength, or put simply, number of bars visible on a mobile phone. This means, so long as the device has an acceptable signal, power can be adjusted accordingly, at both the base station and the device itself, to ensure the overall energy isn’t “wasted”. Hence focusing of the energy is highly desirable in terms of overall energy use.
Any single base-station installation is constrained by national regulations in terms of its maximum power output. Focusing the energy is therefore a key enabler along with the deployment of additional spectrum that allows efficient sharing (multiplexing) of the “energy” resource. The more focused the energy is, the more efficient the overall base station – and this is realised in the form of overall throughput or cell-range.
It is clear, therefore, that the ability to efficiently focus energy leads to more efficient deployment of base stations. This in turn leads to higher overall throughput and/or larger cell footprints, which means fewer base stations are needed to support the same overall set of service requirements. Focusing the energy leads directly to cost efficiencies. The more highly focused the beam or bubble of energy, the greater the cost saving (to reduce the equation to its simplest form). Antenna Arrays are the way in which we focus that energy.
HOW DO ANTENNA ARRAYS FOCUS THE ENERGY?
Single antennas, in general, transmit a signal, oscillating electrical and magnetic field, over a very wide angle – often omnidirectional. The shape and manufacture of the antenna shapes the actual transmit / receive pattern, but in general it is unfocused.
If we add additional antennas alongside the first, and we choose the spacing carefully, we can transmit the same signal from each of the antennas whilst creating constructive and destructive interference patterns. The signals interfere with each other, sometimes adding together (where they are in-phase), sometimes cancelling (where they are out of phase).
It is the constructive interference, where signals from each antenna add together to create a much larger signal, that effectively give us the “focusing” mechanism. The constructive interference is generally in the form of a beam of energy (in a certain direction), or bubble of energy (around a point in space). In other directions, or at other points, the signal is much weaker because the signals from the different antennas destructively interfere and act to cancel each other out.
So here’s two key bits:
- Firstly, the more antennas there are, the more focused the signal, beam or point.
- Secondly, by changing the relative timing of the signal as it is applied to each antenna, we can direct the beam or point of focus. It is much more complex than this in reality, but this simple description allows us to look at why 5G is so special when it comes to these techniques.
WHAT’S SO SPECIAL ABOUT 5G AND ANTENNA ARRAYS?
There are some fundamental differences between 5G and previous generations, but of real interest in terms of antenna arrays is the frequencies for which 5G is relevant. Previous generations were designed and engineered to work in the UHF Band between ~ 700 MHz to 2600 MHz. Here, antennas are relatively large, and using antenna arrays of more than four or eight antennas becomes problematic in terms of cost and physical size / weight.
In contrast 5G allows the use of much higher frequencies, well into the millimetre wave spectrum as well as the low-mid range frequencies already mentioned. At the higher frequencies, antennas are much smaller, allowing many antennas to be used in a single array – perhaps 64 or 256, known as massive antenna arrays. This in turn allows for very focused beam-forming or MIMO (Multiple In Multiple Out) antenna techniques.
Not only does 5G enable access to a much wider range of spectrum, but this in turn allows us to use that spectrum very efficiently – so long as we make use of advanced antenna techniques - utilising arrays. The efficiency gains we can achieve compared to previous generations is very significant, with benchmark figures of 3x that of LTE Advanced, but real-life figures are potentially much, much higher. This gives us outstanding efficiency at the higher millimetre waves, although the reduced range at higher frequencies mean the base stations would be deployed in “high capacity hot-spots”.
With advances in processing capabilities and manufacturing techniques, it is also feasible to deploy massive antenna arrays in mid-range frequencies, where cell footprint is generally larger than for millimetre wave frequencies – leading to highly efficient base station deployments with excellent throughput and coverage.
Another key aspect is that 5G New Radio allows us to access spectrum that is set aside for private networks in unlicensed or shared frequency bands. This is a significant enabler for industrial automation and smart factories, and the associated new business models. These relevant unlicensed frequencies tend to be higher in the spectrum, so massive antenna arrays and the beamforming / MIMO techniques that go with them, are essential parts of many new deployment scenarios and use cases.
THE BOTTOM LINE
The impact of all this is efficiency, which in turn leads to cost-effective deployment of resources / base stations. There are a number of different aspects of 5G that that contribute to the overall efficiency, but it is advanced antenna techniques, and in-particular massive antenna arrays, that give us the means to fully realise the potential of 5G with regards to keeping costs under control whilst massively ramping up capacity and at the same time exploring new use cases and business models.
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