Research and Analysis of TD-SCDMA Uplink Capacity - Advanced Research on Computer Education, Simulation and Modeling - page 129

the relationship between capacity and bit energy-to-noise density ratio (E b /N 0 ).When
the uplink is studied, E b /N 0 is ratio of received signal to noise arrived receiver. It is
from the view of BS. So the study and analysis is not relevant to power of MS
transmitter , path loss and transmission loss. We only think about the signal that has
arrived at BS receiver. The paper are organized as follows. A single cell capacity
function will be deduced in section 2. Multiple cells capacity function will be deduced
in section 3. At last, conclusions are drawn in section 4.

2 Uplink Single Cell Capacity Analysis and Research

Capacity discussed in this paper is user capacity, that is, in the QoS requirements, per
unit area and per bandwidth can accommodate the maximum number of users.
Because single cell model is simple, this section start to analyze it in theoretical. It is
assumed that only one base station in single cell and Omni-directional antenna[5] is
used. The cell contains users.
The following symbolic meaning is interpreted

P is the j -th user power

I is all users power reaching base station.
N is the base station receiver thermal noise.

own

∂

is active factor.

AF

I

is that the whole power that is base station have received at all.

total

From the objective physical meaning, Equation (1) can be defined.

N

∑
=

I = ∂ × P (1)

own AF j

j 1

According to Equation (1), Equation(2) can be drawn

N

∑
=

I = ∂ × P + N (2)

total AF j o

j 1

η

is the uplink capacity percentage due to the j -th user added the single cell.

j

η

is the uplink capacity percentage all users of the single cell

P

j

η = (3)

j

I

total

N

∑
=

η = ∂ ⋅ η

(4)

AF j

j 1

G is processing gain. W is the rate of Spread Spectrum.