What is Zadoff-Chu sequence in LTE?
Zadoff–Chu sequences are used in the 3GPP Long Term Evolution (LTE) air interface in the Primary Synchronization Signal (PSS), random access preamble (PRACH), uplink control channel (PUCCH), uplink traffic channel (PUSCH) and sounding reference signals (SRS).
Why is Zadoff-Chu used in LTE?
Zadoff-Chu sequences ,  are used as random multiple access codes in the LTE system due to their perfect autocorrelation properties i.e., the autocorrelation of a ZC sequence with a non-zero cyclically shifted version of itself is zero.
What is cyclic shift in LTE?
The new mechanism of cyclic shift delay means to delay the space-time streams with different time reference. The cyclic shift can be viewed as an optimization of the MIMO communication channel and this processing is transparent to the receiver.
What is preamble format in LTE?
A preamble is send by UE to gNB over PRACH channel to obtain the UL synchronization. Similar to LTE, in 5G NR there are 64 preambles defined in each time-frequency PRACH occasion. The preamble consists of two parts cyclic prefix (CP) and Preamble Sequence.
Why SSS is placed before PSS?
SSS helps to achieve radio frame synchronization and deduce a pointer towards 1 of 168 Physical layer Cell Identity (PCI) groups. Below diagram shows how PSS and SSS helps finding the Physical Layer Cell ID.
How many sub carriers does PSS?
The PSS is constructed from a frequency-domain ZC sequence of length 63. Transmitted on 6th symbol of slot 0 and slot10 of each radio frame on 72 subcarriers centered around DC.
What does cyclic shift mean?
A circular shift is a special kind of cyclic permutation, which in turn is a special kind of permutation. In computer programming, a bitwise rotation, also known as a circular shift, is a bitwise operation that shifts all bits of its operand.
How many preambles are there in 5G?
In 5G NR, there are 13 types of preamble format supported known as Format 0, Format 1, Format 2,Format 3,Format A1,Format A2,Format A3,Format B1, Format B2, Format B3, Format B4, Format C0, Format C1.
What is backoff timer in LTE?
Backoff Indicator is a special MAC subheader that carries the parameter indicating the time delay between a PRACH and the next PRACH. There are cases where a UE has to send another PRACH after it already sent a PRACH.
What is the use of Zadoff-Chu sequence in DfT-s-OFDM?
Gold sequence is used in CP-OFDM, Zadoff-chu sequence is used in DFT-s-OFDM (for SSS) and m-sequence is used in PSS. • Zadoff-Chu sequences are used to generate NR random-access preambles (PRACH). • It has following unique properties for which it is used. • For PUSCH channel with DFT-S-OFDM physical layer, there is low PAPR Zadoff-Chu mode.
What does shifting a Zadoff Chu sequence mean?
It means that you can create many of orthogonal sequences just by shifting a Zadoff Chu sequence. How convenient it is to create orthogonal sequences.. and you know how important to create orthogonal sequences in many wireless communication.
What is Zadoff—Chu (ZC) sequence in LTE?
In the LTE system, Zadoff—Chu (ZC) sequence is used for the generation and detection of physical random access channel (PRACH) preamble sequence. The key step of PRACH baseband signal generation is to perform a discrete Fourier transform (DFT) of ZC sequence, which is characterized by the root index u and a rotation factor p.
What is an example of Zadoff sequence?
(Column B, C is one example of Zadoff Sequence. B is the real part and C is imaginary part. The plot is the scatter plot of column B, C) ii) Zero Autocorrelation. If you create a sequence using this formula and create another sequence just by shifting the same sequence by N (N can be 1,2,….,size of sequence -1).