China
Africa
Explore chapters and articles related to this topic
Spread spectrum techniques
Published in Geoff Lewis, Communications Technology Handbook, 2013
Gold code sequences. These represent a family of pseudo-random sequences that were defined by R. Gold in 1967 as having a low cross-correlation between each other. As such they can occupy the same signalling channel without producing destructive interference. Because of these properties, Gold codes find applications in code division multiple access (CDMA) or spread spectrum multiple access (SSMA) systems. Each code sequence is produced from a pair of PRBS generators each with n stages by modulo-2 addition. If all the 2n + 1 Gold sequences of period 2n − 1 are concatenated, the resulting sequence period becomes (2n + 1) (2n − 1) = 22n − 1, the same as would be generated by a shift register with 2n cells.
Adaptive Beamforming and Localization
Published in David C. Swanson, ®, 2011
A typical linear MLS generator [8] is seen in Figure 14.14. The notation describing the generator is [N,i,j,k, …] where the sequence is 2N − 1 “chips” long, and i, j, k, and so on are taps from a 1-bit delay line where the bits are XOR’d to produce the MLS output. For example, the generator depicted as [7,3,2,1] has a seven-stage delay line, or register, where the bits in positions 7, 3, 2, and 1 are modulo-2 added (bit exclusive OR denoted as XOR’d) to produce the bit that goes into stage 1 at the next clock pulse. The next clock pulse shifts the bits in stages 1–6 to stages 2–7, where the bit in stage 7 is the MLS output, copies the previous modulo-2 addition result into stage 1, and calculates the next register input for stage 1 by the modulo-2 addition of the bits in elements 7, 3, 2, and 1. Thanks to Galios theory, there are many, many irreducible polynomials from which MLS sequences can be generated. The Gold codes allow a number of nearly maximal sequences to be generated from multiple base MLS sequences of the same length, but different initial conditions and generator stage combinations. The Gold codes simplify the electronics needed to synchronize transmitters and receivers and extract the communication data. A number of useful MLS generators are listed in Table 14.1 which many more generators can be found in an excellent book on the subject by Dixon [9].
*
Published in Moeness Amin, Compressive Sensing for Urban Radar, 2017
The bandwidth corresponding to this waveform is given by B = 1/tc. Several code sequences are used for spread-spectrum signaling like the pseudoran-dom code sequences, Gold code sequences, etc. There is a vast literature available on the design and properties of such code sequences (Gold, 1967; Sarwate and Pursley, 1980).
Parallel Greedy Search for Random Access in Wireless Networks
Published in IETE Technical Review, 2023
Rahul Kumar, Madhusudan Kumar Sinha, Arun Pachai Kannu
Gold codes are non-orthogonal binary sequences with good cross-correlation and autocorrelation properties. Gold code construction gives codes of length , where is any positive integer. Since for sparse signal recovery, we are concerned only with the cross-correlation property, every cyclic shift of gold code sequences that produces a unique code can be used as a codeword. Gold code sequences are periodic with period , thus through the cyclic shift of every code, we can generate a total of codes. Mutual coherence of codebook obtained from Gold codes is given by [25]:
Analysis of Beam Sweeping Techniques for Cell-Discovery in Millimeter Wave Systems
Published in IETE Technical Review, 2023
P. Rashmi, A. Manoj, Arun Pachai Kannu
The cyclic shifts of the root sequences can also be considered as ZC sequences. The first sequence is an all-one sequence , and the shifted versions cannot be used as SS. Hence, in total, we can have ZC sequences of odd prime length L with good correlation properties. Gold codes can also be used for synchronization purposes because of their good cross-correlation properties [25]. In this paper, we use ZC sequences as synchronization signals for multiple BS case.