Chip Rate: This is defined as the number of cycles per second of the modulated carrier. For WCDMA it is 3.84 Mcps. This results in a carrier bandwidth of about 5MHz.
It is the budgeting of power within a system at its various component stages, hence being able to deduce the maximum path loss, cell radius and an approximation of the number of required Node B in the system.
Noise Figure: It is a measure of the degradation in signal-to-noise ratio (SNR) between the input and output ports of the network measured in dB.
Bit Rate: The user’s service bit rate is the ‘bit rate’. For example, speech service has a bit rate of 12.2 kbps. Other data services could use bit rates of 64, 144, 384 Kbps.
Interference
Margin: It is a factor (in
dB) that takes into account the interference generated from the serving as well
as neighboring cells. It depends on the loading assumed for the system while
calculating a link budget. As the load on the cell gradually increases so does
the rise in noise level within the cell commonly referred to as ‘Noise Rise’.
The Noise Rise directly contributes to the Interference Margin.
Noise Rise: It defines the increase in the noise in a cell as the cell loading increases. It is defines as:
10 log 1
-------
1- X
where X is the cell loading and 0<X<1. A cell loading of 75% results in Noise Rise of approximately 6dB. The Noise Rise is a component that contributes to the link budget of a system and also in capacity related calculations and therefore is an essential link between the two…
Eb/No:
it is the ratio of energy per bit to the
interference and noise density for a specified FER (typically 1%). The Eb/No
for the down-link improves at higher speeds. However, in the case of the
up-link, the Eb/No improves at lower speeds.
Processing Gain: The gain achieved by the spreading process and depends on the data rate. i.e. 10 x log10(3840000/data rate)
% Loading (X): % Cell loading defines the percentage to which the cell is loaded. The power level that is determined for traffic channels in the cell will need to be shared by all mobiles in the cell. Therefore the maximum number of mobiles in the cell for dimensioning purposes must be ascertained. This value is generally a fraction of the pole capacity.
The pole capacity is obtained from simulations and is the maximum number of users that can simultaneously use the same RF channel at a point in time. It depends on the kind of service used i.e. the data rate.
Fade
Margin: This is a dB value added to the mobile sensitivity and used to
factor in the effects of
log-normal fading or slow fading to a specified reliability. Log normal or
shadow fading is fading in the signal produced due to terrain and clutter
characteristics in the cell.
The Fade Margin is accounted for by
the reliability factor (or confidence factor) specified by the network operator
as the % of edge or area coverage, and also affects the link budget, cell
spacing and eventually the cost of the network.
To ascertain the Fade Margin, Jakes
curves are used along with the following inputs: