00:00Hi, in the last session we talked about the MIMO concept in 5G, and we discussed that
00:05how 5G RAIN can be benefited from multiple input, multiple output concepts.
00:11Now in this session we will be talking about 5G spectrum.
00:15So spectrum plays an important role in wireless communication.
00:18So first we will understand that what innovations 5G brings in terms of spectrum utilization.
00:24Here you can see that 5G NR spectrum options are divided into two frequency ranges.
00:30First is FR1 or Frequency Range 1 and second is Frequency Range 2 or FR2.
00:37Frequency Range 1 or FR1 includes the bands which are below 6 GHz and having the carrier
00:43bandwidth from 5 MHz to 100 MHz.
00:46So bands in Frequency Range 1 or FR1 have lower frequencies which provides better propagation
00:53characteristics.
00:54So they are ideal for coverage from macro base stations.
00:59Frequency Range 2 or FR2 covers the bands which are above 24 GHz and they can offer
01:05channel bandwidths between 50 MHz to 400 MHz.
01:09However FR2 bands have poor penetrations through obstacles like walls, buildings etc.
01:16But they can offer larger bandwidth.
01:19So these characteristics make them suitable for high density locations and hotspots such
01:24like city centers, stadiums etc.
01:27Now let's see that how the spectrum utilization evolves over time.
01:32Here you can see the allocation and the utilization of spectrum over time.
01:37Green one indicates the 4G and blue one indicates the 5G here.
01:41Initially a significant portion of a newly allocated spectrum is dedicated to 5G.
01:47But over the time more spectrum from the existing 4G spectrum will be reformed to
01:53use for 5G.
01:54And this will allow us to get the benefit of higher spectral efficiency from 5G NR radio.
02:01So it's important to understand that 5G NR brings higher spectral efficiency through
02:06the different mechanisms.
02:08Let's look on two of them now.
02:10First in this example of 20 MHz spectrum, LTE has 100 subcarriers and each of them is
02:1715 kHz wide.
02:19Whereas NR can accommodate 106 subscribers from the same 20 MHz bandwidth at the same
02:2615 kHz spacing.
02:28And this happens due to reduced guard bands.
02:31Additionally NR uses new channel coding options.
02:34While LTE relies on the turbo codes, NR uses low density parity checks codes or LDPC codes
02:41which are significantly more efficient especially for the large transport blocks.
02:47And this makes them ideal for the data channels.
02:49Secondly, NR also employs polar codes which offers about 0.5 dB gain over the turbo codes
02:57which make them suitable for the control traffic.
03:00NR supports wideband carriers which offers up to 100 MHz of bandwidth from bands below
03:066 GHz and up to 400 MHz from the bands which are above 24 GHz.
03:13These bands can also be aggregated through the carrier aggregations to achieve even higher
03:17data rates.
03:19In phase 1 of 5G NR, operators can aggregate up to 16 component carriers and up to 1 GHz
03:26of total spectrum to be utilized.
03:29And these component carriers can be contiguous, non-contiguous, intraband and can be intraband
03:35as well.
03:36So there is a lot of flexibility there in the deployment.
03:40In addition, there is one more spectrum-related concept in NR called bandwidth part.
03:46Most base stations can utilize the wider bandwidths available in 5G.
03:50However, user equipment capabilities can be different for different handsets and hence
03:55it will be more challenging for some UEs to use that larger available bandwidth.
04:00For example, some low-cost smartphones may struggle to utilize the full bandwidth or
04:06the full capacity of the bandwidth.
04:08Even if a UE is capable of using wide bandwidths, but maybe it do not need to use wide bandwidth
04:14continuously.
04:15For example, the UE just transferring a very small amount of data, like notification or
04:21small messages etc.
04:23So there is no need to use wide bandwidth in such needs.
04:27Wide bandwidths also drains more battery.
04:30So it also impacts the battery life of the device.
04:33So considering all these requirements, NR introduced bandwidth part.
04:38A bandwidth part or BWP in short is a subset of contiguous resources block on a carrier.
04:45You can see this in the picture.
04:47Here you have one single carrier at the top and it has multiple bandwidth parts like BWP1
04:53and BWP2.
04:54Like a wider bandwidth part is in blue color and the narrower bandwidth part is in green
04:59color.
05:00Now here is the important thing that each of these bandwidth parts on a carrier, they
05:05can both have different numerology.
05:07This means they can be completely different in subcarrier spacing, symbol duration and
05:12cyclic prefix length etc.
05:15There is also a lot of flexibility that how the bandwidth parts can be set up in a carrier
05:20as seen in the figure.
05:22A UE can be configured with up to four bandwidth parts, but only one can be active at any specific
05:28one point of time.
05:29For example, when a smartphone has a busty data to send, then the network configures
05:35that device for a wider bandwidth part.
05:38And when there is a very little data to send, then the network will configure that UE for
05:42a narrower bandwidth part.
05:44And hence the network resources can be utilized properly and it saves the battery life of
05:49the devices as well.
05:50Okay, so that's it for today.
05:52I believe you get some insights on spectrum allocations in 5G NR.
05:57We discussed about some of the concepts in 5G NR2 like carrier aggregation and bandwidth
06:01part, which are important for optimizing the 5G performance and network efficiency.
06:07In the next session, we will be talking about another important concept in 5G NR and that
06:11is dual connectivity.
06:13So stay tuned for the updates.
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