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Why is SC-FDMA used for uplink transmissions in LTE?
SC-FDMA is preferred for LTE uplink mainly due to its advantage of having low peak-to-average power ratio (PAPR) during signal transmission. It is found that by increasing spreading factor symbol error rate is reduced for SC-FDMA system and for spreading factor of 64 for SNR=20 dB, SER is of the order of 10 -4 .
Why LTE uses OFDMA for DL and SC-FDMA for UL?
In LTE, the OFDMA is used as downlink and SCFDMA as uplink modulation schemes; with OFDM as the basic building block. OFDMA is used for achieving high spectral efficiency in communication system; whereas, SC-FDMA for uplink multiple access scheme in LTE system.
What are the features of FDMA?
Main features: In FDMA, every user shares the frequency channel or satellite transponder simultaneously; however, every user transmits at single frequency. FDMA is compatible with both digital and analog signals. FDMA demands highly efficient filters in the radio hardware, contrary to CDMA and TDMA.
Why are there 12 subcarriers in LTE?
In the downlink, the subcarriers are split into resource blocks. This enables the system to be able to compartmentalise the data across standard numbers of subcarriers. Resource blocks comprise 12 subcarriers, regardless of the overall LTE signal bandwidth. They also cover one slot in the time frame.
Why OFDM is called orthogonal?
In OFDM, the subcarrier frequencies are chosen so that the subcarriers are orthogonal to each other, meaning that crosstalk between the sub-channels is eliminated and inter-carrier guard bands are not required.
What is FDMA explain?
D. F. M. (Frequency Division Multiple Access) FDMA is the wireless implementation of FDM (frequency division multiplexing). Used in satellite transmission and earlier AMPS analog cellular networks, FDMA divides the bandwidth into separate channels, one for each user.
How is SC-FDMA used in LTE uplink?
The LTE Single-Carrier Frequency Division Multiple Access (SC-FDMA) uplink incorporates Reference Signals (RSs) for data demodulation and channel sounding.
Which is Single Carrier Division Multiple Access ( SC-FDMA )?
Single Carrier Frequency Division Multiple Access (SC-FDMA) is a promising technique for high data rate uplink communication and has been adopted by 3GPP for it next generation cellular system, called Long-Term Evolution (LTE). SC-FDMA is a modified form of OFDM with similar throughput performance and complexity.
What is the difference between OFDM and SC-FDMA?
OFDM, Orthogonal Frequency Division Multiplex is the basic format used and this is modified to provide the multiple access scheme: OFDMA, orthogonal frequency division multiple access in the downlink and SC-FDMA, single channel orthogonal frequency division multiple access in the uplink.
Which is better for broadband CDMA or SC-FDMA?
The major problem in extending GSM TDMA and wideband CDMA to broadband systems is the increase in complexity with the multipath signal reception. The main advantage of OFDM, as is for SC-FDMA, is its robustness against multipath signal propagation, which makes it suitable for broadband systems.