Fact-checked by Grok 2 weeks ago

Gold code

A Gold code, also known as a Gold sequence, is a binary pseudorandom sequence of length $2^r - 1 (where r is a positive integer), constructed as the modulo-2 sum (XOR) of two maximal-length sequences (m-sequences) generated by linear feedback shift registers (LFSRs) using a "preferred pair" of primitive polynomials of degree r.^[1]^[2] These sequences, first introduced by Robert Gold in 1967, possess ideal two-level autocorrelation—equal to $2^r - 1 at zero shift and -1 at all nonzero shifts—and bounded cross-correlation between distinct sequences in the set, with a maximum magnitude of approximately $2^{(r+1)/2} + 1.^[1] This combination of properties makes Gold codes particularly valuable for applications requiring reliable signal detection amid interference, such as code-division multiple access (CDMA) systems and global positioning system (GPS) signals.^[1] Gold codes are generated efficiently using pairs of LFSRs with carefully selected tap configurations to ensure the preferred pair condition, which guarantees the desired correlation bounds; for example, when r is odd, the decimation factor e satisfies \gcd(e, r) = 1, and the pair polynomials produce $2^r + 1 distinct sequences forming a large family with uniformly low cross-correlations.^[2] From a coding theory perspective, each Gold sequence corresponds to a codeword in a cyclic linear code of length n = 2^r - 1 and dimension k = 2r, with the code generated by the product of the two primitive polynomials and exhibiting a minimum distance that varies with r (e.g., no codewords of weight less than 5 when r is odd).^[2] The construction allows for the creation of extensive sets of nearly orthogonal sequences—up to $2^r + 1 in size—far larger than what single m-sequences can provide, enabling multiple users or signals to share the same bandwidth without significant mutual interference. These sequences have become foundational in modern telecommunications and navigation technologies due to their balance of length, randomness-like statistical properties, and computational simplicity in hardware implementation via shift registers.^[1] In GPS, for instance, Gold codes of length 1,023 bits (with r = 10) are modulated onto carrier signals at 1.575 GHz to enable precise pseudoranging and anti-jamming resilience, while in CDMA systems such as cdmaOne (IS-95), Gold codes facilitate user separation in multi-access environments.^[1] Ongoing research continues to explore their use in advanced areas such as iterative decoding for error correction and radar signal processing, leveraging their structured yet pseudorandom nature.^[2]

Background Concepts

Linear Feedback Shift Registers

A linear feedback shift register (LFSR) is a type of shift register that incorporates feedback by computing the input bit as a linear combination, modulo 2, of its previous state bits. This linear combination is typically performed using exclusive-OR (XOR) operations on selected bits from the register's stages.^[3] The mechanism produces pseudorandom binary sequences and forms the basis for generating sequences used in applications like coding and synchronization.^[4] The basic structure of an LFSR consists of an n-stage binary shift register, where each stage holds a bit (0 or 1), and feedback taps are defined by the coefficients of a characteristic polynomial of degree n over the finite field GF(2). The polynomial p(x) = x^n + c_{n-1} x^{n-1} + \cdots + c_1 x + c_0, with c_i \in \{0, 1\}, determines which stages are XORed to produce the feedback bit. In the common Fibonacci configuration, the register shifts right on each clock cycle, the output is taken from the least significant bit (LSB), and the feedback bit—computed as \bigoplus_{i=0}^{n-1} c_i s_i—is inserted into the most significant bit (MSB) position.^[4]^[5] In operation, the LFSR is initialized with a non-all-zero state vector to avoid the trivial constant-zero sequence. Upon each clock pulse, the bits shift (right in Fibonacci LFSRs), the feedback bit is calculated from the current state using the polynomial taps, and it replaces the bit shifted out from the opposite end. The sequence output is usually the bit shifted out or a specific stage, such as the LSB. This process repeats deterministically, cycling through states based on the polynomial's properties.^[4]^[5] For a simple illustrative example, consider a 3-stage LFSR with characteristic polynomial x^3 + x^2 + 1, corresponding to feedback taps on the LSB (s_0) and MSB (s_2) (XOR of those bits). Assuming a right-shifting Fibonacci setup with states denoted s_2 s_1 s_0 (MSB to LSB), starting from initial state "111": the transitions are as follows (feedback = s_2 XOR s_0; output = old s_0):

Clock 1: Feedback = 1 XOR 1 = 0; shift to "011" (output: 1)
Clock 2: Feedback = 0 XOR 1 = 1; shift to "101" (output: 1)
Clock 3: Feedback = 1 XOR 1 = 0; shift to "010" (output: 1)
Clock 4: Feedback = 0 XOR 0 = 0; shift to "001" (output: 0)
Clock 5: Feedback = 0 XOR 1 = 1; shift to "100" (output: 1)
Clock 6: Feedback = 1 XOR 0 = 1; shift to "110" (output: 0)
Clock 7: Feedback = 1 XOR 0 = 1; shift to "111" (output: 0)

This yields the periodic output sequence 1, 1, 1, 0, 1, 0, 0 with period 7, as the polynomial is primitive.^[5] Mathematically, the LFSR state at time k can be represented as a column vector \mathbf{S}_k = \begin{pmatrix} s_{k,0} \\ s_{k,1} \\ \vdots \\ s_{k,n-1} \end{pmatrix}, where s_{k,i} \in \{0,1\} are the bits (with s_{k,0} as the LSB). The next state is given by \mathbf{S}_{k+1} = A \mathbf{S}_k \pmod{2}, where A is the n \times n companion matrix of the characteristic polynomial:

A = \begin{pmatrix} 0 & 0 & \cdots & 0 & c_0 \\ 1 & 0 & \cdots & 0 & c_1 \\ 0 & 1 & \cdots & 0 & c_2 \\ \vdots & \vdots & \ddots & \vdots & \vdots \\ 0 & 0 & \cdots & 1 & c_{n-1} \end{pmatrix}

All operations are over GF(2), so multiplication is AND and addition is XOR. This matrix formulation captures the linear recurrence relation governing the sequence.^[6] When the characteristic polynomial is primitive over GF(2), the LFSR produces a maximal length sequence of period $2^n - 1, visiting all non-zero states before repeating.^[3]

Maximal Length Sequences

Maximal length sequences, commonly referred to as m-sequences, are pseudorandom binary sequences produced by linear feedback shift registers employing primitive characteristic polynomials of degree n over the finite field GF(2; these sequences achieve the maximum possible period of $2^n - 1.^[3] Such sequences serve as fundamental building blocks for constructing Gold codes due to their strong pseudorandom characteristics within a periodic framework.^[3] A key property of m-sequences is their balance, wherein each period contains exactly $2^{n-1} ones and $2^{n-1} - 1 zeros, ensuring an nearly equal distribution that approximates true randomness.^[3] They also exhibit two-level autocorrelation, with values of $2^n - 1 at zero shift and -1 at all nonzero shifts modulo the period, making them ideal for applications requiring sharp pulse-like correlation behavior.^[3] These sequences demonstrate near-ideal randomness properties, including uniform distribution and low discrepancy, which hold effectively for degrees up to approximately n = 32.^[7] To generate an m-sequence, the characteristic polynomial must be primitive over GF(2), guaranteeing the full period without shorter cycles; for instance, with n=3 and the polynomial x^3 + x + 1, starting from a nonzero initial state, the sequence is $1, 1, 1, 0, 0, 1, 0, repeating every 7 bits. The run-length distribution further underscores their pseudorandom nature: half of all runs have length 1, one-fourth have length 2, one-eighth have length 3, and so on, up to one run of length n.^[3] The mathematical formulation of the autocorrelation function for an m-sequence \{s_k\} of period N = 2^n - 1 is given by

C(\tau) = \sum_{k=0}^{N-1} (-1)^{s_k + s_{k+\tau}} = \begin{cases} N & \tau \equiv 0 \pmod{N} \\ -1 & \tau \not\equiv 0 \pmod{N} \end{cases}

This two-valued periodic autocorrelation quantifies the sequence's self-similarity and is central to its utility in signal processing.^[3]

Generation

Preferred Polynomial Pairs

Preferred polynomial pairs are pairs of primitive polynomials of degree n over the Galois field GF(2) that generate maximal length sequences (m-sequences) suitable for constructing Gold codes with optimal cross-correlation properties. These pairs ensure that the resulting Gold sequences exhibit bounded low cross-correlations, making them ideal for multi-user systems where interference minimization is critical. The selection of such pairs was originally detailed by Robert Gold as a means to produce large families of binary sequences for spread-spectrum multiplexing. Preferred pairs are defined such that the cross-correlation between the generated m-sequences is three-valued {-1, -t(n), t(n)+2} where t(n)=2^{(n+1)/2}+1 for odd n, ensuring the Gold family has bounded cross-correlations.^[8] The criteria for preferred polynomial pairs emphasize the cross-correlation between the m-sequences produced by the two polynomials p(x) and q(x). Specifically, one polynomial serves as a reference primitive polynomial generating an m-sequence, while the second is chosen such that their cross-correlation remains low across all shifts; this is achieved when the second polynomial corresponds to an m-sequence satisfying trace conditions in GF(2^n) that balance the distribution of symbol agreements and disagreements. Such pairs yield cross-correlations confined to a small set of values, optimizing the performance of the derived Gold codes. Preferred pairs are optimal for odd n; they are also defined for even n (particularly n \equiv 2 \pmod{4}), but with slightly weaker bounds. Representative examples include, for n=5, the pair (x^5 + x^2 + 1, x^5 + x^3 + 1), which generates m-sequences of length 31 suitable for Gold code families of size 33. For n=10, a preferred pair is (x^{10} + x^3 + 1, x^{10} + x^9 + x^8 + x^6 + x^3 + x^2 + 1), producing sequences of length 1023, as used in GPS C/A codes.^[9] These examples are drawn from tables in foundational and applied literature on sequence generation.^[8]^[10] The number of preferred polynomial pairs grows approximately as $2^n for large n, providing ample choices for generating distinct Gold code sets. For small degrees, such as up to n=6, exhaustive lists of all such pairs have been compiled, facilitating complete analysis and implementation.^[11] A pair is deemed preferred if the number of solutions to the defining equations in GF(2^n)—derived from the field trace function applied to linear combinations of primitive elements—is balanced, ensuring the cross-correlation \theta(\tau) satisfies |\theta(\tau)| \leq 2^{(n+2)/2} for all nonzero shifts \tau. This bound represents the optimal achievable cross-correlation magnitude for families of this size, as established in the theory of binary sequences.

Sequence Construction

Gold codes are constructed by combining two maximal-length sequences (m-sequences), denoted as a(t) and b(t), generated from a preferred pair of linear feedback shift registers (LFSRs) with primitive polynomials of degree n, each having period N = 2^n - 1.^[12] The resulting Gold code family consists of the 2^n + 1 distinct sequences: a(t), b(t), and g_k(t) = a(t) \oplus b(t + k \mod N) for k = 1, 2, \dots, N (i.e., all non-trivial phase shifts of b(t)), where \oplus denotes the modulo-2 sum (XOR operation).^[13] This process yields a family of $2^n + 1 distinct binary sequences of length N, including the original m-sequences a(t) and b(t). The preferred pair ensures desirable correlation properties, though the construction itself relies on systematic phase shifting.^[12] In practice, the sequences are implemented using LFSRs to generate a(t) with a fixed initial state, while b(t) is phase-shifted by integer amounts before the XOR operation; decimation techniques may be applied for computational efficiency in hardware realizations.^[14] Mathematically, the i-th Gold sequence can be expressed as

g^{(i)}(t) = a(t) + b(t + \tau_i) \pmod{2},

where \tau_i are the selected phase shifts that produce the distinct family members.^[12] Note that for degrees without preferred pairs (e.g., small even n like 2), the construction may not yield distinct sequences with ideal properties; examples are typically given for n ≥ 5 where preferred pairs exist.

Properties

Autocorrelation Function

The autocorrelation function of a Gold code measures its similarity to a time-shifted version of itself, which is crucial for assessing its pseudorandom properties and suitability for synchronization in spread-spectrum systems. For a binary Gold code sequence g(t) of length N = 2^n - 1, where t = 0, 1, \dots, N-1, the periodic autocorrelation at shift \tau is defined in binary form as C(\tau) = \sum_{t=0}^{N-1} g(t) \cdot g((t + \tau) \mod N) \mod 2, but more commonly analyzed in bipolar representation where the sequence is mapped to \pm 1 values, yielding C_g(\tau) = \sum_{t=0}^{N-1} (-1)^{g(t) + g(t + \tau \mod N)}.^[12]^[15] Gold codes inherit near-ideal two-level autocorrelation properties from their underlying m-sequences, with C_g(0) = N at zero shift and out-of-phase values approximately -1 for \tau \not\equiv 0 \pmod{N}, though the function actually exhibits three levels due to the XOR construction from preferred polynomial pairs. Specifically, the non-zero shift autocorrelation takes values in the set \{-1, -t(n), t(n) - 2\}, where t(n) = 2^{(n+1)/2} + 1 for odd n (e.g., for n=5, N=31, levels are -1, -9, 7), providing bounded sidelobes that remain low relative to the peak for large n.^[12]^[15] Compared to m-sequences, which have strictly two-level autocorrelation (N at zero and exactly -1 otherwise), Gold codes show slightly degraded sidelobe suppression but retain sufficient impulsiveness for practical synchronization tasks in applications like GPS.^[12]^[15] Regarding balance, which relates to the pseudorandomness and power spectral density, approximately half of the Gold codes in a preferred set are balanced, meaning the number of 1s and 0s differs by at most 1; the exact number of balanced codes is $2^{n-1} + 1 for odd n, with the remainder exhibiting small imbalances of \pm 2^{n-2}.^[16]

Cross-Correlation Bounds

The cross-correlation between two distinct Gold codes g_i and g_j in a family of length N = 2^n - 1, at lag \tau, is defined as

\theta(\tau) = \sum_{t=0}^{N-1} (-1)^{g_i(t) + g_j(t + \tau)},

where the codes are binary sequences typically mapped from {0,1} to \{\pm 1\} for correlation computation.^[12] When generated from preferred polynomial pairs, the cross-correlation \theta(\tau) takes only three distinct values for all \tau, ensuring low interference in multi-user scenarios. For odd n, these values are -1, -1 + 2^{(n+1)/2}, and -1 - 2^{(n+1)/2}, yielding the bound |\theta(\tau)| \leq 2^{(n+1)/2} + 1. For even n, the values are -1, -1 + 2^{(n+2)/2}, and -1 - 2^{(n+2)/2}, with the bound |\theta(\tau)| \leq 2^{(n+2)/2} + 1. These exact values and bounds arise from the algebraic structure of the underlying maximal length sequences.^[12] The distribution of these values over the N possible shifts \tau is balanced, particularly for odd n, where each of the three levels occurs approximately N/3 times. This even spread minimizes peak interference across lags.^[12] The bounds are derived from the Welch lower bound on the maximum cross-correlation in a family of M = 2^n + 1 sequences, which Gold codes nearly achieve, combined with the finite field properties ensuring three-valued correlations for preferred pairs. Specifically, the construction exploits quadratic residues in \mathrm{GF}(2^n) to select polynomials whose decimations yield the desired low cross-correlations between shifted m-sequences. As a representative example, for n=5 (N=31), the values are -1, $7, and -9, with maximum |\theta(\tau)| = 9, illustrating the near-equal distribution.^[12]

Applications

GPS Signal Encoding

The Coarse/Acquisition (C/A) code in the Global Positioning System (GPS) utilizes Gold codes to provide unique identification for each satellite's civilian signal on the L1 frequency band. These codes are generated using two preferred polynomials for 10-stage linear feedback shift registers (LFSRs): G_1(x) = x^{10} + x^3 + 1 and G_2(x) = x^{10} + x^9 + x^8 + x^6 + x^3 + x^2 + 1.^[17] The resulting Gold code for each satellite is formed by the modulo-2 sum (XOR) of the G1 sequence and a phase-shifted version of the G2 sequence, yielding a period of 1023 chips that repeats every millisecond.^[17] GPS employs 37 unique C/A codes, corresponding to Pseudo-Random Noise (PRN) numbers 1 through 37, one per operational satellite (with an expanded set defined up to PRN 63 for future use). Each code is distinguished by specific phase selections applied to the G2 register, as detailed in the GPS interface specification; for example, PRN 1 uses a G2 delay of 5 chips relative to G1.^[17] These phase taps ensure that the codes form a set with favorable correlation properties derived from the preferred polynomial pair. The C/A code operates at a chip rate of 1.023 megachips per second (Mcps), spreading the signal across a bandwidth of approximately 2 MHz centered on the L1 carrier frequency of 1575.42 MHz.^[17] The C/A code modulates the 50 bits per second (bps) navigation message data through binary phase-shift keying (BPSK), where the data bits are modulo-2 summed with the code sequence before carrier modulation. This spreading technique implements code-division multiple access (CDMA) among the satellites, allowing a GPS receiver to distinguish signals from multiple satellites simultaneously by correlating with the specific PRN code.^[17] The low cross-correlation between different Gold codes (typically bounded at -24 dB or better for non-zero shifts) enables reliable separation of the satellite signals in a shared frequency band, while the sharp main-lobe autocorrelation peak facilitates code acquisition and synchronization in the receiver.^[17] As an example, the C/A code sequence for PRN 1 begins with the first 10 chips in binary as 1 1 0 0 1 0 0 0 0 0 (equivalent to octal 1440 in GPS notation, where the leading digit represents the first chip).^[18] The full 1023-chip sequence for PRN 1 is generated by initializing both LFSRs to all ones, applying the 5-chip G2 delay, and clocking them synchronously while XORing the outputs until the period completes.^[17]

CDMA Systems

Gold codes play a crucial role as spreading sequences in code-division multiple-access (CDMA) systems, where they enable the separation of multiple users transmitting simultaneously over the same frequency band. In early 3G systems such as WCDMA, Gold codes are utilized for scrambling to differentiate signals from base stations or user equipment, supporting user separation with long scrambling codes derived from degree-25 Gold sequences, segmented into 38,400-chip frames (corresponding to 10 ms periods at 3.84 Mcps) for enhanced synchronization and data transmission.^[19] The primary advantages of Gold codes in these CDMA applications stem from their bounded cross-correlation values, which effectively suppress multi-user interference by limiting the overlap between distinct user signals. This property allows more users to share the channel without significant performance degradation, as the interference power remains controlled even in asynchronous environments. Furthermore, their generation via paired linear feedback shift registers facilitates low-complexity hardware realization, making them practical for resource-constrained mobile and base station implementations.^[20]^[21] To address bursty data patterns common in wireless traffic, variants such as shortened or truncated Gold codes are employed, where sequences are clipped to match packet durations while preserving favorable autocorrelation for detection. These adaptations are particularly useful for preamble sequences in burst transmissions. Additionally, Gold codes can be combined with complementary families like Kasami codes to generate larger sets of sequences with low cross-correlation, expanding capacity in dense multi-user scenarios.^[22]^[23] In various wireless standards, Gold codes are applied to pilot channels for aiding receiver synchronization and channel estimation, transmitting known patterns to facilitate initial acquisition without carrying user data. For instance, in uplink CDMA designs, orthogonal Gold codes serve as pilot synchronization channels to enable rapid cell search across slots. In satellite CDMA communications, Gold codes provide robust spreading for reliable signal discrimination amid propagation delays and multipath effects.^[24]^[25] Performance benefits in CDMA systems arise from the processing gain of N = 2^n - 1, which enhances signal-to-noise resilience and yields bit error rate (BER) reductions through despreading, with typical improvements of 3-6 dB in multi-user settings compared to single-user baselines. Interference levels are inherently bounded by the cross-correlation threshold of Gold codes, typically around 2^{(n+2)/2} in magnitude, enabling support for dozens of simultaneous users while maintaining acceptable BER under practical loading conditions.^[20]^[26]

History and Development

Gold codes were first introduced by Robert Gold, an engineer at Magnavox, in 1967 through his seminal paper "Optimal Binary Sequences for Spread Spectrum Multiplexing," published in IEEE Transactions on Information Theory.^[12] In this work, Gold described a method to generate families of binary sequences with low cross-correlation by combining two preferred m-sequences via modulo-2 addition, addressing the need for multiple nearly orthogonal codes in spread-spectrum systems. This innovation built on earlier research into linear feedback shift registers and maximal-length sequences during the 1960s, amid growing interest in anti-jam communications for military applications. The sequences gained prominence in the development of satellite navigation systems. During the conceptualization of the Global Positioning System (GPS) in the early 1970s, Gold codes were selected for the coarse/acquisition (C/A) signal due to their favorable correlation properties, enabling multiple satellites to transmit on the same frequency without significant interference. This decision was formalized at a key meeting in September 1973, known as the "Lonely Halls" symposium, where CDMA techniques incorporating Gold codes were adopted for GPS.^[27] Gold's contributions were recognized in subsequent GPS signal specifications, with the 1,023-chip C/A code (r=10) implemented starting from the system's initial satellite launches in 1978. In parallel, Gold codes influenced the evolution of code-division multiple access (CDMA) for cellular communications. They were incorporated into standards like IS-95 (cdmaOne) in the 1990s for pseudorandom noise spreading and later in UMTS (3G) for user and channel scrambling, facilitating efficient multi-user access in wireless networks. Ongoing research since the 2000s has extended their application to advanced error-correcting codes and radar systems, leveraging their mathematical structure for improved performance in interference-prone environments.

References

[1]
[PDF] E11 Lecture 7: Gold Codes
○ Each seed gives a different Gold code. ○ Each code is quite different than the others. 19. Page 20. Naming a Gold Code. ○ To uniquely define a Gold code:.
[2]
[PDF] Iterative decoding of Gold sequences - HAL
Mar 17, 2016 · In this paper, we first provide a synthesis of Gold sequence properties from the viewpoint of coding theory. A Gold sequence is a codeword of a ...
[3]
Shift Register Sequences | Semantic Scholar
Jun 1, 1981 · The Revised Edition of Shift Register Sequences contains a comprehensive bibliography of some 400 entries which cover the literature ...Missing: book | Show results with:book
[4]
[PDF] Linear Feedback Shift Registers - Koc Lab
A linearly connected shift register of n cells, each of which is holding a state variable si ∈ {0,1} and set of coefficients ci ∈ {0,1}, for.
[5]
[PDF] Linear Feedback Shift Registers (LFSRs)
• Note: state of the LFSR ⇔ polynomial of degree n-1. • Example: P(x) ... • Example: Characteristic polynomial is P(x) = x3 + x + 1. • Beginning at all ...
[6]
Linear Feedback Shift Registers for the Uninitiated, Part VIII: Matrix ...
Nov 21, 2017 · The third approach for representing the state of the LFSR is to use vectors of bits along with the companion matrix of the characteristic polynomial.
[7]
Randomness Measurements and m-Sequences (Chapter 5)
In Section 5.1, we present Golomb's three randomness postulates for binary sequences, namely the balance property, the run property, and the (ideal) two-level ...Missing: length | Show results with:length
[8]
Gold Sequence Generator - Simulink - MathWorks
The Preferred polynomial (1) and Preferred polynomial (2) parameters determine the preferred pair of sequences and the feedback connections for the shift ...
[9]
[PDF] Simulation of Gold Code Sequences for Spread Spectrum Application
Jul 20, 2014 · The following table provides a list of preferred pairs used for. Gold sequence. Table 1 : List of Preferred Pairs n N. Preferred. Polynomial [1].
[10]
(PDF) Formation of Minimax Ensembles of Aperiodic Gold Codes
Apr 29, 2020 · ... Numbers of preferred pairs of primitive polynomials that ...<|control11|><|separator|>
[11]
Optimal binary sequences for spread spectrum multiplexing (Corresp.)
**Summary of Abstract and Key Details on Gold Sequences:**
[12]
comm.GoldSequence - Generate Gold sequence from ... - MathWorks
The comm.GoldSequence System object generates a binary sequence with small periodic cross-correlation properties from a bounded set of sequences.
[13]
Gold code generator using LFSRs - GaussianWaves
Jun 9, 2015 · A sample hardware implementation for generating a length 127 Gold code – using the preferred pairs ([7,3,2,1],[7,3]) is shown in Figure 2. Here ...
[14]
[PDF] CORRELATION PROPERTIES AND MULTIPLE-ACCESS ...
Figure-3(a) shows the autocorrelation of one of the Gold codes. It is obvious that this autocorrelation plot is quadruple-valued, in consistency with the ...
[15]
[PDF] Gold Codes
Gold Codes. Balanced Gold Codes. Balanced Gold Codes. Example 7.9. Consider the following preferred primitive polynomial pair g1(D) = D. 3. + D + 1 = (13)8 g2(D) ...
[16]
[PDF] GPS Interface Specification IS-GPS-200, Revision N - August 2022
Aug 1, 2022 · 3.2.1.3.1 Expanded C/A Code (GPS III and GPS IIIF) ... a linear pattern which is generated using the same code generator polynomial as the one used ...
[17]
[PDF] 1995-SPS-signal-specification.pdf - GPS.gov
chips of the C/A code for PRN Signal Assembly No. 1 are: 1100100000). ** C/A codes 34 and 37 are common. *** PRN sequences 33 through 37 are reserved for ...
[18]
Codes used in CDMA - GaussianWaves
Feb 28, 2011 · IS-95 CDMA Standard uses three types of codes namely 1) Long code 2) Short code and 3) Walsh Hadamard codes. IS-95 Architecture. Long Code: Long ...
[19]
[PDF] ETSI TS 125 213 V9.2.0 (2010-10)
The resulting sequences thus constitute segments of a set of Gold sequences. The scrambling codes are repeated for every 10 ms radio frame. Let x and y be the.
[20]
Multiple-Access Interference of Gold Codes in a DS-CDMA System
Mar 31, 2015 · The results indicate that certain sets of Gold codes have good cross-correlation properties that make them resistant to multiple-access ...Missing: advantages | Show results with:advantages
[21]
[PDF] Code Division Multiple Access (CDMA) - Complex To Real
The spreading quality of the sequence is an added dimensionality and benefit in CDMA systems. Gold sequences. Combining two m-sequences creates Gold codes.
[22]
Preamble code structure and detection method and apparatus
46A-D and 47A-D are graphs illustrating correlation responses of matched filters to length-120 repeated codeword preamble codes constructed from truncated Gold ...
[23]
[PDF] New Multi Level Spreading Codes for DS CDMA Communication
Walsh, Gold and Kasami codes are the popularly used Binary (2-level) user codes. This paper proposes new multi level spreading codes constructed using ternary ...
[24]
Pilot synchronization channel structure for CDMA mobile ...
The PSC is an orthogonal Gold code or Walsh code without modulation, and is transmitted once every slot. For all wireless cells, the PSC are all the same.
[25]
Code selection
Gold codes and Kasami codes, if carefully selected, have autocorrelation functions and cross-correlation functions close to the ideal codes. By "carefully ...<|control11|><|separator|>
[26]
System performance criteria in CDMA networks using gold codes
Thirdly, we investigated the number of simultaneous users in a CDMA system using Gold codes for the worst case and the average case of mutual interference.Missing: shortened | Show results with:shortened<|separator|>