Contents
- 1 How the OVSF code is generated?
- 2 What is a spreading code?
- 3 What is OVSF in UMTS?
- 4 What are OVSF codes?
- 5 What is a chipping code?
- 6 What is TDMA technique?
- 7 What is chip in wireless communication?
- 8 What is UMTS in mobile network?
- 9 What is the purpose of the OVSF code?
- 10 What does OVSF code stand for in WCDMA?
- 11 How to generate an OVSF code generator block?
How the OVSF code is generated?
The OVSF Code Generator block generates an OVSF code from a set of orthogonal codes. OVSF codes were first introduced for 3G communication systems. OVSF codes are primarily used to preserve orthogonality between different channels in a communication system. It follows by induction that the rows of CN are orthogonal.
What is a spreading code?
In DSSS, a spreading code is used to map each data bit in the original signal to multiple bits in the transmitted signal. The pseudorandom code (spreading code) spreads the input data across a wider frequency range compared to the input frequency. In the frequency domain, the output signals appear as noise.
How many OVSF codes are there in Wcdma?
Downlink Channel Code Preset
| Compressed Mode with 384k DL DPCH(Non-HSDPA) | |
|---|---|
| PICH Channelization Code | 16 |
| AICH Channelization Code | 10 |
| WCDMA DL Channel Codes | |
| DPCH 15 ksps (OVSF 256) Channelization Code | 12 |
What is OVSF in UMTS?
OVSF code channel assignment with dynamic code set and buffering adjustment for UMTS. In WCDMA, orthogonal variable spreading factor (OVSF) codes are assigned to different users to preserve the orthogonality between users’ physical channels. The data rate supported by an OVSF code depends on its spreading factor (SF).
What are OVSF codes?
Orthogonal variable spreading factor (OVSF) is an implementation of code division multiple access (CDMA) where before each signal is transmitted, the signal is spread over a wide spectrum range through the use of a user’s code. These codes are derived from an OVSF code tree, and each user is given a different code.
What is a channelization code?
The channelization codes are Orthogonal Variable Spreading Factor codes that preserves the orthogonality between a user’s different physical channels. The OVSF codes can be defined using a code tree.
What is a chipping code?
DSSS technology breaks down the transmitted stream of data into small pieces across a frequency channel. A redundant bit pattern (known as a chipping code) is generated for each bit transmitted. Generally, the longer the chipping code, the more likely it is that the original transmitted data will be properly received.
What is TDMA technique?
Time-division multiple access (TDMA) is a channel access method for shared-medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot.
What is primary scrambling code?
A primary scramble code is the product of the Scramble Code field entry and 16. Therefore, the primary scramble code set contains all multiples of 16 from 0 through 8176. A secondary scramble code is the sum of the non-zero Scramble Offset field entry and the primary scramble code.
What is chip in wireless communication?
In digital communications, a chip is a pulse of a direct-sequence spread spectrum (DSSS) code, such as a pseudo-random noise (PN) code sequence used in direct-sequence code division multiple access (CDMA) channel access techniques.
What is UMTS in mobile network?
UMTS or the Universal Mobile Telecommunications System is a third generation wireless network technology which allows speeds of up to 2Mbps. UMTS is based on the WCDMA technology, which is why these terms have become interchangeable.
What is channelization code and scrambling code?
Channelization codes are generated recursively to form a binary tree structure (see Figure 15.20). Spreading is used in combination with scrambling. Scrambling is used on top of spreading to separate mobile terminals or cells from each other. Scrambling does not change the chip rate nor the bandwidth.
What is the purpose of the OVSF code?
OVSF codes are primarily used to preserve orthogonality between different channels in a communication system. OVSF codes are defined as the rows of an N-by-N matrix, C N, which is defined recursively as follows. First, define C 1 = [1].
What does OVSF code stand for in WCDMA?
• OVSF stands for Orthogonal Variable Spreading Factor. They are also referred as channelization codes. They are used to separate data and control channels from same UE • It preserves orthogonality between these control and data channels. Following are useful features of OVSF codes used in WCDMA system.
How are OVSF codes used to preserve orthogonality?
OVSF codes are primarily used to preserve orthogonality between different channels in a communication system. OVSF codes are defined as the rows of an N-by-N matrix, C N , which is defined recursively as follows. First, define C 1 = [1].
How to generate an OVSF code generator block?
You specify the code the OVSF Code Generator block outputs by two parameters in the block’s dialog: the Spreading factor, which is the length of the code, and the Code index, which must be an integer in the range [0, 1, , N – 1], where N is the spreading factor.