Can anyone explain about Reverse CDMA Channel of IS-95 in CDMA? alaxander 12-May-2008 10:37:51 PMComments It carries both signalling and traffic from MS to BSS. Posted by waqqas1 From MS to BSS It carries traffic and signaling information. FEC code rate is 1/3, the code symbol rate = 28,800 symbols/sec, 6 code symbols/modulation symbol, and the PN rate is 1.2288 MHz Modulation is 64-ary orthogonal Walsh functions, each period of the Walsh function is repeated for four chips of the PN code Walsh symbol rate is 1.2288 MHz/(4 chips per Walsh chip)/(64 Walsh chips per Walsh symbol) = 4,800 modulation symbols/ second Reverse CDMA Channel consists of 2 42-1 logical channels One of the logical channels is permanently and uniquely associated with each MS. The channel does not change upon handoff. Reverse link addressing is accomplished through manipulation of period 2 42-1 Long Code, which is part of the spreading process. The reverse CDMA Channel does not use strict orthogonality in any sense to separate logical channels. Rather, it uses a very long period spreading code, in distinct phases. The correlations between stations are not zero, but they are acceptably small Posted by srini_murali Fundamentally different from the forward channels 1.)Uses OQPSK for power efficiency 2.) QPSK demodulation is easy 3.) 869-894 MHz range. 4.) No spreading of the data using orthogonal codes 5.) Same orthogonal codes are used for WAVEFORM encoding 6.)Two types of logical channels: The access channels and the reverse traffic channels Posted by sagitraz |
Posted: 13-May-2008 09:33:46 AM By: sagitraz Fundamentally different from the forward channels 1.)Uses OQPSK for power efficiency 2.) QPSK demodulation is easy 3.) 869-894 MHz range. 4.) No spreading of the data using orthogonal codes 5.) Same orthogonal codes are used for WAVEFORM encoding 6.)Two types of logical channels: The access channels and the reverse traffic channels | |
Posted: 13-May-2008 11:38:45 AM By: srini_murali From MS to BSS It carries traffic and signaling information. FEC code rate is 1/3, the code symbol rate = 28,800 symbols/sec, 6 code symbols/modulation symbol, and the PN rate is 1.2288 MHz Modulation is 64-ary orthogonal Walsh functions, each period of the Walsh function is repeated for four chips of the PN code Walsh symbol rate is 1.2288 MHz/(4 chips per Walsh chip)/(64 Walsh chips per Walsh symbol) = 4,800 modulation symbols/ second Reverse CDMA Channel consists of 2 42-1 logical channels One of the logical channels is permanently and uniquely associated with each MS. The channel does not change upon handoff. Reverse link addressing is accomplished through manipulation of period 2 42-1 Long Code, which is part of the spreading process. The reverse CDMA Channel does not use strict orthogonality in any sense to separate logical channels. Rather, it uses a very long period spreading code, in distinct phases. The correlations between stations are not zero, but they are acceptably small | |
Posted: 31-December-2008 12:01:01 AM By: waqqas1 It carries both signalling and traffic from MS to BSS. |