31-03-2014, 02:28 PM
3G Complete Knowledge
Basics of 3G
WCDMA Bandwidth
FDD – 5 MHZ of Paired
TDD – 5 MHZ Only
SF and Data rate
SF is lower when data rate is higher
SF and Power Relation
When lower the SF then more power required
SF and Coverage relation
SF is high then coverage will be high
CPICH Power -:
It takes about 8 to 10% of the total NodeB Power .For a 20W (43dBm) NodeB, CPICH is around 2W (33dBm).
In urban areas where in-building coverage is taken care of by in-building installations, the CPICH may sometimes go as low as 5% because:
The coverage area is small since users are close to the site, and
More power can be allocated to traffic channels.
Noise Rise –
For every new user added to the service addition noise is added to the network. This is each new user causes a “noise rise” . In theory the “noise rise” is defined as the ratio of total received wideband power to the noise power.
Higher “nose rise” value implies more users are allowed on the network, and each user has to transmit the higher power to over come the higher noise level. This means smaller path loss can be tolerate and the cell radius is reduced.
CPICH Ec/No
The CPICH Ec/No is used to determine the „quality“ of the received signal. It gives the received energy per received chip divided by the band‘s power density. The „quality“ is the primary CPICH‘s signal strength in relation to the cell noise. (Please note, that transport channel quality is determined by BLER, BER, etc. )
If the UE supports GSM, then it must be capable to make measurements in the GSM bands, too. The measurements are based on the
Scrambling Code
Scrambling code ：GOLD sequence.
Scrambling code period : 10ms ,or 38400 chips.
The code used for scrambling of uplink DPCCH/DPDCH may be of either long or short type, There are 224 long and 224 short uplink scrambling codes. Uplink scrambling codes are assigned by higher layers.
For downlink physical channels, a total of 218-1 = 262,143 scrambling codes can be generated. Only scrambling codes k = 0, 1, …, 8191 are used.
SC used to separate the cells in N/W
In UL it is used to differentiate the terminals.
After the Channelization Codes, the data stream is multiplied by a special code to distinguish between different transmitters.
Scrambling codes are not orthogonal so they do not need to be synchronized
The separation of scrambling codes is proportional to the code length – longer codes, better separation (but not 100%)
Scrambling codes are 38400 chips long
Basics of 3G
WCDMA Bandwidth
FDD – 5 MHZ of Paired
TDD – 5 MHZ Only
SF and Data rate
SF is lower when data rate is higher
SF and Power Relation
When lower the SF then more power required
SF and Coverage relation
SF is high then coverage will be high
CPICH Power -:
It takes about 8 to 10% of the total NodeB Power .For a 20W (43dBm) NodeB, CPICH is around 2W (33dBm).
In urban areas where in-building coverage is taken care of by in-building installations, the CPICH may sometimes go as low as 5% because:
The coverage area is small since users are close to the site, and
More power can be allocated to traffic channels.
Noise Rise –
For every new user added to the service addition noise is added to the network. This is each new user causes a “noise rise” . In theory the “noise rise” is defined as the ratio of total received wideband power to the noise power.
Higher “nose rise” value implies more users are allowed on the network, and each user has to transmit the higher power to over come the higher noise level. This means smaller path loss can be tolerate and the cell radius is reduced.
CPICH Ec/No
The CPICH Ec/No is used to determine the „quality“ of the received signal. It gives the received energy per received chip divided by the band‘s power density. The „quality“ is the primary CPICH‘s signal strength in relation to the cell noise. (Please note, that transport channel quality is determined by BLER, BER, etc. )
If the UE supports GSM, then it must be capable to make measurements in the GSM bands, too. The measurements are based on the
Scrambling Code
Scrambling code ：GOLD sequence.
Scrambling code period : 10ms ,or 38400 chips.
The code used for scrambling of uplink DPCCH/DPDCH may be of either long or short type, There are 224 long and 224 short uplink scrambling codes. Uplink scrambling codes are assigned by higher layers.
For downlink physical channels, a total of 218-1 = 262,143 scrambling codes can be generated. Only scrambling codes k = 0, 1, …, 8191 are used.
SC used to separate the cells in N/W
In UL it is used to differentiate the terminals.
After the Channelization Codes, the data stream is multiplied by a special code to distinguish between different transmitters.
Scrambling codes are not orthogonal so they do not need to be synchronized
The separation of scrambling codes is proportional to the code length – longer codes, better separation (but not 100%)
Scrambling codes are 38400 chips long