What is carrier frequency offset in OFDM?
What is carrier frequency offset in OFDM?
Carrier frequency offset (CFO) is one of most well-known disturbances for OFDM. It generates inter-carrier interference (ICI) and degrades OFDM performance [1]. In order to mitigate the negative influence, CFO is usually estimated and compensated accordingly during OFDM reception.
What is carrier phase offset?
The carrier–envelope offset phase (or absolute phase) of a pulse is defined as the difference between the optical phase of the carrier wave and the envelope position, the latter being converted to a phase value. Figure 1 shows pulses with different values of the carrier–envelope offset phase.
What is frequency Offset in communication?
In order to reduce the interference from the fringe area transmitters transmitting in the same channels, a method named frequency offset is often used.
What is frequency offset correction?
The symptom of this offset is a phase rotation of constellation points after FFT (frequency domain). The CFO can be corrected with the help of short preamble (Coarse) long preamble (Fine). And the SFO can be corrected using the pilot sub-carriers in each OFDM symbol.
What are the effect of frequency offset in OFDM system?
Frequency offset reduces the signal power and destroys orthogonality among subcarriers leading to the intercarrier interference (ICI). It is necessary to analyze how the frequency offset affects the performance of OFDM systems.
What are the effects of frequency offset in OFDM system?
What is the purpose of carrier frequency?
The purpose of the carrier is usually either to transmit the information through space as an electromagnetic wave (as in radio communication), or to allow several carriers at different frequencies to share a common physical transmission medium by frequency division multiplexing (as in a cable television system).
What is the role of the carrier frequency in modulation?
A carrier frequency differing from the incoming signal by a specific amount, the IF frequency, and coupled into a nonlinear device produces the modulation function.
What is carrier frequency error?
Carrier frequency offset (CFO) is one of many non-ideal conditions that may affect in baseband receiver design. This phenomenon can be attributed to two important factors: frequency mismatch in the transmitter and the receiver oscillators; and the Doppler effect as the transmitter or the receiver is moving.
What is the purpose of using carrier frequency?
Why are carrier frequency offsets inevitable In framebased OFDM?
In framebased OFDM systems, both the residual CFO tracking and the SCO tracking are inevitable, because the receiver may operate for a long period of time. In packet-based OFDM systems, however, the influences of these two offsets depend on the packet length and the magnitude of the offsets.
What is the precision tolerance for carrier frequency offset?
Carrier frequency offset. In a standard-compliant communication system, such as the IEEE 802.11 WLAN the oscillator precision tolerance is specified to be less than ±20 ppm, so that CFO is in the range from – 40 ppm to +40 ppm.
What does carrier frequency offset ( CFO ) mean?
( June 2015) Carrier frequency offset (CFO) is one of many non-ideal conditions that may affect in baseband receiver design. In designing a baseband receiver, we should notice not only the degradation invoked by non-ideal channel and noise, we should also regard RF and analog parts as the main consideration.
How is orthogonality maintained in an OFDM system?
When this occurs, the received signal will be shifted in frequency. For an OFDM system, the orthogonality among sub carriers is maintained only if the receiver uses a local oscillation signal that is synchronous with the carrier signal contained in the received signal.