The Base Station transmitter signal is, however, the composite of many channels (with a minimum of four). The Pilot channel is unmodulated (Walsh code 0); it consists of only the final spreading sequence (short sequences). The Pilot channel is used by all mobiles linked to a cell as a coherent phase reference and also provides … Read more
Here I write about EVDO (HSD) reverse channel in short or summarize defination. The EVDO channels for the reverse connection have a similar structure as for CDMA2000. The reverse link for 1xEV-DO has a structure similar to that for CDMA2000. In EV-DO all signalling is performed on the data channel and this means that there … Read more
This graphically demonstrates why interleaving data improves error correction performance of data transmission systems. In the top Image, data is sequentially read out of a buffer than goes by rows. No interleaving is employed. The data is read and transmitted in numerical order. During transmission, data blocks 5 through 8 are corrupted by some interference. … Read more
The forward link possesses many features that are specific to EV-DO, having been optimised for data transmission, particularly in the downlink direction. Average continuous rates of 600 kbps per sector are possible. This is a six fold increase over CDMA2000 1X and is provided largely by the ability of 1xEV-DO to negotiate increased data rates … Read more
A number of channels are transmitted in the forward direction to enable signalling, data and other capabilities to be handled. These channels include the Traffic channel, MAC channel, Control channel and Pilot. These are time division multiplexed. Traffic Channel – This channels uses Quadrature Phase Shift Keying (QPSK) modulation for data rates up to 1.2288 … Read more
Pilot Channel Physical Layer The Pilot channel is essentially the short codes operating on their assigned PN offset. This is accomplished by selecting Walsh code 0 which is 64 zeroes (remember, the first code in any Walsh code set is always composed of all zeroes) as the Walsh code modulation data. In addition, the channel … Read more
If the modulation data changes, QPSK modulation makes one symbol change each period. If the data is the same, then QPSK and OQPSK do not change state. However, if the data changes, then OQPSK will make at least one symbol change and possibly two changes in a single period. QPSK Makes one Symbol Change Every … Read more
The sync channel messages include the CDMA protocol revision supported by the cell site, the minimum protocol revision supported by a CDMA mobile in order to work with the cell site, the system and network identification numbers for the cell site, the PN offset of the cell site, the paging channel data rate, and all … Read more