This document discusses calculations for channel capacity in a CDMA system. It contains the following key points: 1. Channel capacity in a CDMA system depends on the level of interference in the system. To maximize capacity, power control and interference reduction are needed. 2. Blocking occurs in a CDMA system when total interference exceeds noise. Equations are provided to calculate interference levels and number of channels based on factors like bandwidth, data rate, and number of users. 3. The reverse link pole capacity for a CDMA system using Rate Set 2 is 19 users or approximately 12.3 Erlangs per sector, assuming a three sector site. This represents the maximum number of users that can be added

1. Perhitungan Kapasitas Kanal
Pada Sistem CDMA
Arif Hidayat ST

2. Overview System CDMA
• Kapasitas System CDMA tergantung dari
bayaknya interferensi dari system tersebut
• Untuk memaksimalkan kapasitas dari
system CDMA perlu dilakukan pengaturan
power dan mengurangi interferensi
system.
• Bloking pada sistem CDMA terjadi ketika
total interferensy melebihi Noise

3. Persamaan Energy Per Bit
• Assuming:
• P denotes the received power from each subscriber at the base
station antenna
• R denotes the data rate (9600 bps for Rate Set 1, 14400 bps for Rate
Set 2)
• Power control is perfect
• Subscribers are transmitting just enough power to be received
• Uniform subscriber distribution

4. Interferensi Total
• W=Bandwidth of the channel
• N = Jumlah User (Kanal N)

5. Energi Bit dibanding Noise
• Jika dilakukan perbandingan Energi Bit
dibandingkan dengan Noise di dapat :
• Pendekatan

6. Perhitungan Level Interferensi
• Persamaan di atas adalah pada kondisi
ideal
• Pada aplikasinya terdapat interferensi
yang didapat dari cell lain sehingga di
dapat persamaan

7. Perhitungan level Interferensi
Io = Interference power density impacted by
other cells, and the number of users with
an average voice or data activity rate
f = Ratio of out of cell (inter-cell) interference
power to in cell (intra-cell) interference
power. This factor is used to adjust the
capacity of a single cell to account for the
Interference generated by other users in a multiple
cell system.
=Average voice or data activity factor
=Thermal noise

8. Perhitungan Level Interferensi
• Sehingga Persamaan Total Energi Bit
dibanding dengan nilai Interferensi
menjadi
• Dengan melakukan pendekatan di dapat

9. Perhitungan Jumlah Kanal
• Pendekatan Nilai N

10. Kapasitas Kanal Reverse
• Persamaan Kapasitas Kanal Reverse
Io= Total received signal
No=Thermal noise power
Eb=Energy per bit
Ratio of Signal energy bit to the sum of interference and noise
adjusted fo imperfect power control
W = Bandwidth of the channel

11. Kapasitas Kanal Reverse Lanjutan
R =Data rate
W /R =Processing gain
f = Ratio of out of cell (inter-cell) interference
power to in cell (intra-cell) interference power.
This factor is used to adjust the capacity of a
single cell to account for the interference
generated by other users in a multiple cell
system.
Ρ =Average voice or data
Gs = Sectorization gain

12. Adjusted Eb/Io
• The adjusted Eb/(No+Io) requirement to account
for imperfect power control (power control
deviation) can be determined by:
Signal / (Interference plus noise) ratio
requirement under perfect power control
Standard deviation in imperfect power
control
Constant value equal to ln(10)/10

13. Rasio Power Intra dan Inter Cell
• Some reverse link pole equations may use
the term F, where F is defined as the ratio
of in cell (intra-cell) interference power to
the sum of out of cell (inter-cell)
interference power and in cell (intra-cell)
interference power. F is related to f by the
following equation.

14. Referse N Capacity Final
• Persamaan Referse N Capacity Final
Assuming the following values for the various parameters, the reverse link pole
capacity for an IS-95 Rate Set 2 site would be 19 users or roughly 12.3
Erlangs per sector (assuming an Erlang B model with 2% grade of service)
for a three sector site (57 users per site). This value represents the pole
capacity or the point at which no more users can be added without seriously
degrading the quality of the system.
= Bandwidth of the channel (only one CDMA Channel) 1228800 Hz
= Data rate 14400 bps
= Ratio of out of cell (inter-cell) interference power to in cell 0.7
= Average voice or data activity factor 0.4

15. Referse Pole Capacity Calculation
=Sectorization gain per sector for a three
sector site 2.4/3
= Signal / (Interference plus noise) ratio
requirement under perfect power
control 6.5 dB
= Standard deviation in imperfect power
control 2.5
= Constant value ln(10)/10

16. Reverse Pole Capacity Lanjutan