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What is OFDM numerology?
©3G4G In the context of 3GPP 5G standardization contributions, the term numerology refers to the configuration of waveform parameters, and different numerologies are considered as OFDM-based sub-frames having different parameters such as subcarrier spacing/symbol time, CP size, etc.
Why does 5G have multiple numerology?
Mixing different numerologies on a carrier can cause interference with subcarriers of another numerology. While this provides the flexibility for diverse services to be sent on the same carrier frequency, it also introduces new challenges with interference between the different services.
Why different subcarrier spacing in 5G?
Wider subcarrier spacing would provide better resistance to such increased Doppler shifts at higher frequency bands. Furthermore, 5G NR provides a flexible solution to support various applications by choosing an appropriate configuration. For example, when higher Δf is used, it results in a shorter slot duration.
What do you mean by subcarrier spacing?
Subcarrier spacing is equal to the reciprocal of the symbol time. As a result of the longer symbol time, the subcarrier size and spacing decreases from 312.5 KHz to 78.125 KHz. The narrow subcarrier spacing allows better equalization and therefore enhanced channel robustness.
What is a frame in 5G?
A frame has duration of 10 ms which consists of 10 subframes having 1ms duration each similar to LTE technology. Each subfame can have 2μ slots. Each slot typically consists of 14 OFDM symbols. The radio frame of 10 ms are transmitted continuously as per TDD topology one after the other.
How many subcarriers are in 5G?
5G NR can choose subcarrier spacing from 15kHz to 240kHz, with a maximum 3300 subcarriers in simultaneous use on one channel.
What is the subcarrier spacing in 5G?
15kHz to 240kHz
5G NR can choose subcarrier spacing from 15kHz to 240kHz, with a maximum 3300 subcarriers in simultaneous use on one channel. However, channels can be no more than 400MHz wide. The standard is frequency agnostic, meaning any subcarrier configuration can be used on any band.
What is subcarrier in 5G?
In 5G NR, subcarrier spacing of 15, 30, 60, 120 and 240 KHz are supported. The numerology (u = 0) represents subcarrier spacing of 15 kHz which is same as LTE. And as you see in the second column the subcarrier spacing other than 15KHz, for 5G NR.
What is slot format in 5G?
Slot formats are a fundamentally new concept in 5G NR. They help to realize different downlink and uplink allocations, particularly in time division duplex (TDD) mode. Based on an example with 120 kHz subcarrier spacing, the video explains some unique characteristics compared to TD-LTE.
Is the OFDM symbol shortened by half in higher numerology?
So effectively, an OFDM symbol is shortened by half in the next higher numerology. Scaling by powers of two is beneficial as it maintains the symbol boundaries across numerologies, which simplifies mixing different numerologies on the same carrier.
Which is better NR or LTE mixed numerology?
NR will also have the capability to operate with mixed numerology on the same RF carrier and will have an even higher flexibility than LTE in terms of frequency domain scheduling and multiplexing of devices within a base station RF carrier.
How does numerology relate to the frequency domain?
Numerology corresponds to one subcarrier spacing in the frequency domain. NR supports a flexible numerology with a range of subcarrier spacings, based on scaling a baseline subcarrier spacing of 15 kHz. By scaling a reference subcarrier spacing by an integer N, different numerologies can be defined.
How many OFDM symbols are in a subframe?
A subframe is in turn divided into slots consisting of 14 OFDM symbols each, which means that the duration of the slot in milliseconds is dependent on the numerology.