CODE DIVISION DUPLEXING SYSTEM. Shashwat Shriparv email@example.com InfinitySoft. INTRODUCTION. Reducing interference in a cellular system is the most effective approach to increasing radio capacity and transmission data rate in the wireless environment.
To utilize spectrum efficiently, two transmission techniques need to be considered:
a multiple access scheme
a duplexing system
The industry has already established the best multiple access scheme, code-division multiple access (CDMA), for 3G systems.
Currently there exist only two duplexing technologies in wireless communications,
Two types of interference remain in FDD:
So it can only be used for small confined area systems
Rxx(T )= 0 for T =0
=d for T!=0,within window T0
Rxy (T) = d for all T, within window T0,Where T0 is a correlation window, d can be zero or low correlation value.
They arrive at the receiver of Code C1 at different times due to the multipaths caused by different reflectors.
Because of the cross-correlation property, the desired code to be received is C1
However, many C1 codes can be received due to the effects of the multipaths.
This does not occur though; due to the auto-correlation property, only Code C1 at time t1 is received
Smart code sequences have two properties:
mobility management and call processing.
The handoff function is carried by the selective distribution unit (SDU).
The separated functions are placed on the gateways to the core network.
The demo of carrying voice over IP from mobile to mobile and mobile to landline was successful.
The CDD system’s future IP core network will follow this approach.
The cost will be lower, and add-on features can be very flexible and easy.
cells with multiple frequencies assigned in each cell.