What is subcarrier in OFDM?
Both OFDM and OFDMA divided a channel into subcarriers through a mathematical function known as an inverse fast Fourier transform (IFFT). The spacing of the subcarriers is orthogonal, so they will not interfere with one another despite the lack of guard bands between them. Each OFDM subcarrier is 312.5 KHz.
What is meant by subcarrier?
A subcarrier is a sideband of a radio frequency carrier wave, which is modulated to send additional information. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio broadcast.
How do you choose subcarrier spacing in OFDM?
Choosing the first subcarrier to have a frequency such that it has an integer number of cycles in a symbol period, and setting the spacing between adjacent subcarriers (subcarrier bandwidth) to be BSC = B/L, where B is the nominal bandwidth (equal to data rate), and L is the number of subcarriers, ensures that all …
What does orthogonal mean in OFDM?
In a perfect OFDM signal, Orthogonality prevents interference between overlapping carriers. In FDM systems, any overlap in the spectrums of adjacent signals will result in interference. In OFDM systems, the subcarriers will interfere with each other only if there is a loss of orthogonality.
What does DC subcarrier indicate?
What does the DC subcarrier indicate? Explanation: All the subcarriers of an OFDM symbol do not carry useful data. In OFDM and OFDMA PHY layers, the DC subcarrier is the subcarrier whose frequency is equal to the RF centre frequency of the transmitting station.
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 a subcarrier in 5G?
What is subcarrier bandwidth in LTE?
In addition to this the subcarriers spacing is 15 kHz, i.e. the LTE subcarriers are spaced 15 kHz apart from each other. Each subcarrier is able to carry data at a maximum rate of 15 ksps (kilosymbols per second). This gives a 20 MHz bandwidth system a raw symbol rate of 18 Msps.
What is subcarrier modulation?
A subcarrier is a secondary modulated signal frequency modulated into the main frequency (the carrier) to provide an additional channel of transmission. It allows for a single transmission to carry more than one separate signal. The letter is the signal that she wants to transmit. The envelope is the carrier frequency.
What is subcarrier spacing in 5G?
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 the condition for handoff?
What is the condition for handoff? Explanation: Handoff occurs when a mobile moves into a different cell while a conversation is in progress. The MSC automatically transfers the call to a new channel belonging to the new base station.
What is an OFDM subcarrier?
Fifty-two of the subcarriers are used to carry modulated data; four of the subcarriers function as pilot carriers; and eight of the subcarriers serve as guard bands. OFDM are sometimes also referred to as OFDM tones. In this blog series, we will use both terms interchangeably. Each OFDM subcarrier is 312.5 KHz.
What are the different types of subcarriers for OFDMA?
Just like with OFDM, there are three types of subcarriers for OFDMA, as follows: Data Subcarriers: These subcarriers will use the same modulation and coding schemes (MCSs) as 802.11ac and two new MCSs with the addition of 1024-QAM.
What is the subcarrier spacing in OFDMA?
The narrow subcarrier spacing allows better equalization and therefore enhanced channel robustness. Because of the 78.125 KHz spacing, an OFDMA 20 MHz channel consists of a total of 256 subcarriers (tones) as depicted in Figure 2.
How many subcarriers are there in OFDMA 20 MHz?
Because of the 78.125 KHz spacing, an OFDMA 20 MHz channel consists of a total of 256 subcarriers (tones) as depicted in Figure 2. Just like with OFDM, there are three types of subcarriers for OFDMA, as follows: