Digital Communications and LFSR Properties

A specific arrangement of 0s and 1s in a code period that represents a unique state of the n-column generator (n-set) and occurs only once per code period.

A state with all '0's, which is not allowed as it stops the generator from generating.

A specific type of sequence generated by a linear feedback shift register (LFSR), characterized by its unique statistical properties and a specific structure.

The number of slots (positions) within an m-sequence that contain a '1' or '0' value.

The function that measures the similarity between a code and its shifted version.

A measure of how well a signal can be recovered from a noisy channel. A high autocorrelation indicates strong signal presence.

The function that measures the similarity between two different codes.

A special type of code with exceptional properties for detecting signals and reducing interference, particularly in multipath fading environments.

A sequence of logical 1s and 0s that follows a specific pattern, often pseudo-random. The transitions between 0 and 1 happen at specific time intervals (ti).

The time interval between transitions in a code sequence (0 → 1 or 1 → 0).

The rate of change (frequency) of the code sequence. It indicates how many code changes happen in a given time (Tt).

A type of digital sequence generator that creates a long, repeating pattern of 1s and 0s. It uses a shift register and feedback loop to generate the sequence.

The length of the longest possible sequence that can be generated by an n-column shift register. It is calculated as 2n-1 clock periods.

A function that measures the similarity between a code sequence and a shifted version of itself. It is used to analyze the randomness of code sequences. In m-sequences, it is -1 for most shifts, and only varies for specific shifts.

A process where you add two binary sequences together, with the result being 0 if both bits are the same, and 1 otherwise.

The process of aligning two or more sequences to ensure they start at the same time.

The length of time it takes for an m-sequence to repeat.

A function that measures the similarity between two signals at different time offsets.

The result of adding two or more m-sequences together, often used to create sequences with desirable properties.

Sequences generated by adding two different m-sequences of the same length.

Adding m-sequences of different lengths results in a longer sequence with non-maximal properties.

The time offset between two signals, used to measure how well they align.

A non-maximal code with good properties for distinguishing signals from background interference, particularly in communication scenarios with multiple signals.

A type of code specifically designed for optimal ranging, offering quick synchronization of very long codes. These codes are valuable in applications requiring accurate distance measurements.

In a DSSS signal, a code sequence modified by the information signal, followed by a modulation scheme like BFSK, QPSK, etc. The information signal is combined with the code sequence through a modulus-2 operation.

Used for eliminating unwanted signals in multi-channel synchronized communication. They allow for the selective reception of desired compressed signals and the filtering of noise.

A sequence of '1's and '0's generated by a linear feedback shift register (LFSR). m-sequences possess unique statistical properties and a specific structure, making them ideal for signal detection and ranging.

A signal that uses a code sequence to spread the signal across a wider bandwidth. It is often used in wireless communication to combat interference and multipath fading.

A sequence of bits (0s or 1s) that is repeated to create the spreading code for DSSS signaling.

A specific type of DSSS modulation where the data bits are directly multiplied by the spreading code before transmission.

A signal that carries information with a specific frequency and phase. The frequency of the carrier signal is much higher than the signal being transmitted.

The time it takes for the spreading code to repeat itself. It is an important parameter in determining the bandwidth and performance of the DSSS signal.

The ratio of the code period to the chip rate. It represents the spreading factor of the DSSS signal.

The total number of physical channels in a single cell in a given frequency band divided by the total bandwidth.

The ratio of signal power (S) to interference power (I) in a hexagonal cell, given as 3 times the number of physical channels.

The minimum S/I ratio for a hexagonal cell, which is calculated as the square root of 3 times the number of physical channels.

A formula that relates the efficiency of an FDMA system to the total bandwidth, channel bandwidth, and the minimum S/I ratio. It's calculated as the total bandwidth divided by the channel bandwidth multiplied by the square root of the minimum S/I ratio divided by 6.

The efficiency of an FDMA system with a path loss exponent of 4 is calculated as the total bandwidth divided by the channel bandwidth multiplied by the square root of 2 times the minimum S/I ratio divided by 3.

The efficiency of a TDMA system is similar to FDMA, but it considers the number of time multiplexed channels (k) within each frequency channel. The efficiency is calculated as the total bandwidth divided by the channel bandwidth multiplied by the number of time multiplexed channels.

A combined system that uses both Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) to divide the available resources.

A specific application where the total bandwidth (Bv) is 12.5 MHz, divided into channels of 200 kHz and each channel further divided into 8 time slots. The minimum S/I ratio is required to be 18 dB.