How many sub channels will be required for OFDM?

How many sub channels will be required for OFDM?

Commercial Applications of OFDM With IEEE 802.11g, each channel occupies 16.25 MHz of bandwidth at the 2.4GHz frequency range. In addition, each channel is divided into 52 sub-carriers of 312.5 kHz. Together, these sub-carriers overlap to fully utilize the 16.25 MHz channel bandwidth dedicated per channel.

What are OFDM channels?

OFDM is a subset of frequency division multiplexing in which a single channel utilizes multiple sub-carriers on adjacent frequencies. In addition the sub-carriers in an OFDM system are overlapping to maximize spectral efficiency. Ordinarily, overlapping adjacent channels can interfere with one another.

How do you calculate the number of subcarriers in OFDM?

Consider the symbols X(0) = 1, X(1) = 0, X(2) = -1 and X(3) = j. Since number of symbols is 4, the number of subcarriers is N = 4. The generated OFDM samples without cyclic prefix are given by the 4 pt IFFT i.e.

How many symbols are there in OFDM?

Downlink. LTE FDD uses 10ms frames, divided into 20 sub-frames or slots (of 0.5ms each). Each sub-frame uses 7 OFDM symbols, each with a cyclic prefix.

Is OFDM used in 2.4 Ghz?

OFDM-based wireless LANs will be implemented in the 2.4GHz ISM band as well as the 5GHz band. OFDM WLANs provide very high data rates, resilience to multipath and extended operating range.

What is sub carrier 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 are Docsis channels?

DOCSIS Channels DOCSIS stands for Data Over Cable Service Interface Specification and is a technology standard. Your version of DOCSIS directly relates to upstream and downstream channels a cable modem supports, so it is a standard that you need to pay attention to when getting your cable modem.

What is the sub carrier spacing between sub carriers in 4g system?

In addition to this the subcarriers spacing is 15 kHz, i.e. the LTE subcarriers are spaced 15 kHz apart from each other. To maintain orthogonality, this gives a symbol rate of 1 / 15 kHz = of 66.7 µs.

How is OFDM calculated?

Thus the bandwidth of the OFDM baseband signal is N/2*delta_f,delta_f is the sub-carrier frequency spacing. The sub-carrier frequency spacing delta_f =1/Ts= 1/(Td * N), Ts is the OFDM symbol duration,Td is the sampling symbol duration and equal to the smapling time interval。 Thus Td=1/fs, fs is the DAC sampling rate.

What is channel estimation in OFDM?

Channel estimation plays an important part in an OFDM system. It is used for increasing the capacity of orthogonal frequency division multiple access (OFDMA) systems by improving the system performance in terms of bit error rate.

How does OFDM provide high data rate?

By transmitting a large number of separate carriers, each conveying a low data rate stream, OFDM can attain high data rates. By properly choosing the symbol duration and carrier spacing, efficient modulation and demodulation of the signal is possible.

How orthogonality is achieved in OFDM?

In this simple OFDM system there are N sinusoidal input signals. Each subcarrier transmits one bit of information (N bits total) as indicated by its presence or absence in the output spectrum. The frequency of each subcarrier is selected to form an orthogonal signal set.