Packet Data Services (RF Environment)

Packet data services have different implications when introduced into a
radio environment as compared to a fixed-network environment. More
specifically for the radio link, how packet data is handled is dependent on
whether the radio link is sharing its resources with voice services or is a data
only use. The data-only possibility is available with CDMA2000 1xEV-DO if
data services are only permitted on the new channel. However, regardless of
this issue, when involved with the wireless link, data services are still a best
effort. In addition, signaling traffic has higher priority than voice but voice
services and circuit switched, have a higher priority than packet data.
Regarding packet data resource dimension, it is important to remember
that the packet session is considered active when data is being transferred.
During this process, a dedicated FCH and/or DCCH for traffic signaling and
power control exists between the mobile and the network. In addition, the
high-speed supplemental channel can be utilized for large data transfers.
An important issue that needs to be considered in the allocation of system
resources is that while the session is active, channel elements as well as
Walsh codes are consumed for use by the subscriber and system independent
if data is actually being transferred.
The packet session is alternatively considered dormant when there is no
data being transferred, but a PPP link is maintained between the Packet
Data Server Network (PDSN) and the subscriber. It is important to also note
that no system resources are consumed relative to channel elements or
Walsh codes while the packet session is considered dormant.