In 2009 at least two operators in Indonesia are ready and have been marketed blackberries CDMA (code division multiple access). After the previous Smart Telecom launched CDMA blackberries facility in early November, ready for the next Indosat following the end of 2009. Before the choice, it’s good to learn and find out first what is CDMA?
According to wikipedia, Code division multiple access (CDMA) is a form of the multiplex (not a modulation scheme) and a common access method that divides the channel is not based on time (as in TDMA) or frequency (as in FDMA), but by way of coding data with a special code associated with each channel that exists and use properties of constructive interference of the special codes to perform the multiplex.
CDMA technology was first used in World War II (military technology) by the English allies to foil German efforts disrupt their transmission. Allies decided to transmit not only on one frequency, but at some frequency, Germany made it difficult to capture the full signal.
Advantages CDMA
CDMA technology itself has many advantages when applied in mobile systems. The benefits include:
[1] It takes only one radio is required for some sectors / cells.
[2] No need equalizer to overcome the signal spectrum disorders.
[3] can be merged with other access methods, does not require a timer (guard time) to see the range of time and guard band (guard band) to maintain the inter-channel interference.
[4] It does not take frequency allocation and management of
[5] has a soft capacity to limit the access users.
[6] has the protection of the process of tapping.
Features CDMA
[1] a narrow band message signal (narrowband) will be duplicated with the spread of broadband signal (wideband) or pseudonoise code
[2] Each user has a pseudonoise (PN) code itself alone.
[3] Soft capacity limit: the system performance will change for all users as soon as the user number increases.
[4] Near-far problem (near-far problem)
[5] Interference limited: power control is needed
[6] Wide bandwidth raises diversity, so use the rake receiver
[7] will require all computers ever made by humans on earth to break the code of one and a half a conversation in a CDMA system!
