Home / rf optimization / Page 2

Soft Handoff Gain for CDMA

Soft handoff is the term that is normally associated with the fact that a CDMA system makes a connection to a target cell prior to releasing (breaking) from the source site, commonly referred to as “make-before-break”. A hard handoff, associated with AMPS, GSM, or USDC, requires that the signal strength from the target cell be … Read more

Defination and work of Eb/No in CDMA

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

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

Global Positioning System – GPS

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

How Antenna Downtilting selection for cdma ?

Downtilting is the method of effectively adjusting the vertical radiation pattern of the antenna to increase the amount of power radiated downwards. Downtilting can be used to increase the amount of coverage close to the site where “nulls” (holes) may exist due to the effective height of the antenna. Downtilting can also be used to … Read more

Sectorization Gain in CDMA

Sectorization gain can be somewhat of a misleading term. One could think of the  sectorization gain as more of a reduction factor. For an omni site, the sectorization gain is one. With a sector site, one could initially try to multiply the resulting capacity of an omni site (or single sector) by the number of … Read more

Power Control Inaccuracy in CDMA

CDMA means all depedancy on power control here i write on Power Control Inaccuracy in cdma. Traffic capacity of CDMA systems is increased by implementing an appropriate power control scheme to equalize the performance of all subscribers in the system. The appropriate power control scheme reduces the interference to the other adjacent cells. The less … Read more

Conventional Blocking Analysis for CDMA

Conventional Blocking formula and its Analysis for cdma. In AMPS and TDMA systems, voice/traffic channels are assigned to users as long as they are available. Given the required offered traffic, the Erlang B model is used to determine the number of traffic channels required to provide a predetermined grade of service. The Erlang B model … Read more

Forward Channel Structure in CDMA

Here i write down on how Forward Channel works in CDMA ? and its Structure. The following figure shows an example of the code channels transmitted by a base station. Out of the 64 code channels available for use, the example depicts the Pilot Channel (always required), one Sync channel, seven Paging Channels (the maximum … Read more

Reverse Channel Structure in CDMA

The Reverse CDMA Channel is composed of Access Channels and Reverse Traffic Channels. These channels share the same CDMA frequency assignment. Each Traffic Channel is identified by a distinct user long code sequence and each Access Channel is identified by a distinct Access Channel long code sequence. The following figure shows as example of the … Read more