What is the Zadoff Chu modulation scheme?
A Zadoff–Chu (ZC) sequence, also referred to as Chu sequence or Frank–Zadoff–Chu (FZC) sequence, is a complex-valued mathematical sequence which, when applied to a signal, gives rise to a new signal of constant amplitude.
Why Zadoff Chu used in LTE?
Zadoff-Chu sequences [7], [8] 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. This technique can prevent from unintentional beamforming when the same signal is sent through different space-time streams.
What is root sequence?
The Logical Root Sequence Index is the value of RACH_ROOT_SEQUENCE which is the logical index for the Zadoff-Chu sequence used for PRACH preamble generation.
What is purpose of cyclic shift?
What is PRACH preamble?
The PRACH preamble consists of a cyclic prefix, useful part of the sequence and then a guard period which is simply an unused portion of time up to the end of the last subframe occupied by the PRACH. This guard period allows for timing uncertainty due to the UE to eNodeB distance.
What is a cyclic rotation?
START. Rotate an array to the right by a given number of steps. An array A consisting of N integers is given. Rotation of the array means that each element is shifted right by one index, and the last element of the array is moved to the first place.
What is the range of RSI in LTE?
The highest average precisions obtained for RSI collision detection were 61% and 60% for the 800 MHz and 1800 MHz frequency bands, respectively.
What is PCI and RSI in LTE?
This work focuses on applying supervised techniques for detecting two known LTE network conflicts, namely Physical Cell Identity (PCI) conflicts and Root Sequence Index (RSI) collisions.
What is PRACH root sequence index?
Logical root sequence index prach . SequenceIndex determines the returned physical root Zadoff-Chu sequence index RootSequence , based on TS 38.211 Table 6.3. 3.1-3 and Table 6.3. 3.1-4. However, if the preamble index within the cell, specified by prach.
What is MSG2 in LTE?
ii)The second message (MSG2) is RAR, with which the eNB transmits the message to the device if there is no collision. This message includes a temporary cell-radio network temporary identifier (TC-RNTI) and a timing advance (TA) command (i.e., to adjust the device transmit timing).
What are circular shifts used for?
Circular shifts are used often in cryptography in order to permute bit sequences. Unfortunately, many programming languages, including C, do not have operators or standard functions for circular shifting, even though virtually all processors have bitwise operation instructions for it (e.g. Intel x86 has ROL and ROR).
What is binary rotation?
Bit rotation is an operation similar to shift except that the bits that fall off at one end are put back to the other end. In left rotation, the bits that fall off at left end are put back at right end. In right rotation, the bits that fall off at the right end are put back at the left end.
What is the auto correlation of a Zadoff–Chu sequence with itself?
The auto correlation of a Zadoff–Chu sequence with a cyclically shifted version of itself is zero, i.e., it is non-zero only at one instant which corresponds to the cyclic shift. 4. The cross-correlation between two prime length Zadoff–Chu sequences, i.e. different values of .
What is discrete Fourier transform of a Zadoff–Chu sequence?
is prime, the Discrete Fourier Transform of a Zadoff–Chu sequence is another Zadoff–Chu sequence conjugated, scaled and time scaled. . 3. The auto correlation of a Zadoff–Chu sequence with a cyclically shifted version of itself is zero, i.e., it is non-zero only at one instant which corresponds to the cyclic shift.
Can Zadoff–Chu sequences be used as uplink reference-signal sequences?
where u is the index of the Zadoff–Chu sequence within the set of Zadoff–Chu sequences of length MZC. From the point of view of small power variations in both the frequency and time domains, Zadoff–Chu sequences would thus be excellent as uplink reference-signal sequences.
What is a cyclically shifted Zadoff-Chu sequence?
When cyclically shifted versions of a Zadoff–Chu sequence are imposed upon a signal the resulting set of signals detected at the receiver are uncorrelated with one another. They are named after Solomon A. Zadoff, David C. Chu and Robert L. Frank.