cdma technology optimization
PN Code Generation PN Code Generation PN codes are generated from prime polynomials using modulo 2 arithmetic. The state machines generating these codes are very simple and consist of shift registers and XOR gates . Masking will cause the generator to produce the same sequence, but offset in time PN Offset (Masking) Masking … Read more
• Definition: Orthogonal functions have zero correlation. Two binary sequences are orthogonal if the process of “XORing” them results in an equal number of 1’s and 0’s. Example: 0000 (XOR) 0101 —— 0101 • Generation Sequence: – Seed – Repeat: right & below – Invert: diagonally The above table of … Read more
Traffic Channel Definitions In analog systems, the traffic channels (or voice channels) are synonymous with the physical transceiver hardware. The nature of CDMA technology implies that the effective traffic carrying capacity of a CDMA carrier varies in accordance with the interference density in the band and also depends on various CDMA system parameters. From the … Read more
There are various parameters and terms which come into play when discussing PN offsets and their function in CDMA. System Time All base station digital transmissions are referenced to a common CDMA system-wide time scale that uses the Global Positioning System (GPS) time scale, which is traceable to and synchronous with Universal Coordinated Time (UTC). … Read more
Power control – already being applied in 2nd and 3rd generation networks – has high potential for improvement of the performance of mobile networks. Main benefits are: 1. It can bring down the interference in up- and downlink and hence enhances the capacity of the networks. 2. Additionally it helps to keep down the uplink-power … Read more
In determining RF coverage in CDMA systems, the effect of interference generated from the serving cell as well as the neighboring cells must be considered, this is in contrast to the RF coverage analysis for AMPS cells where interference mainly affects the frequency assignment but not the coverage. The interference margin is dependent upon the … Read more
Eb/No corresponds to energy per bit over interference plus noise density for a given target FER (typical FER target is 1%). In digital communications, it is customary to designate one-sided noise density with No. In CDMA, interference is dominated by the noise generated due to other users in the system. Here No, is refers to … Read more
CDMA forward channel carrier power varies greatly depending on how many traffic channels are in use, the characteristics of the users voices, the Forward Power Control settings as requested by each subscriber unit in use, and the power allocated for overhead functions (Pilot, Page and Sync). An approximation of the CDMA forward channel carrier power … Read more
Antenna beamwidth is measured in degrees between the half power points (3 dB) of the major lobe of the antenna, Beamwidth can be expressed in terms of azimuth (horizontal or H-plane) and elevation (vertical or E-plane). The predominant type of antenna configuration within urban areas at PCS frequencies will be three sectored. This implies that … Read more
The Global Positioning System (GPS) is a radio-navigation system that employs RF transmitters in 24 satellites. The satellite configuration when completed will guarantee that a GPS receiver located anywhere on earth can receive RF signals from at least four satellites 24 hours a day (with unobstructed visibility). For commercial use, each satellite transmits unique bi-phase … Read more