User's Manual

Product Technical Specification & Customer Design Guidelines
20 Proprietary and Confidential - Contents subject to change 2400074
eHRPD (Enhanced High Rate Packet Data) is an enhancement of 1xEV-DO that
enables LTE to CDMA handover.
To optimize for data, there are some fundamental characteristics and differences
between 1X and 1xEV-DO, including:
• The network has dedicated spectrum (1.25 MHz) for data traffic using
1xEV-DO standard, so resources don’t compete with 1X data/voice (hybrid
mode used to monitor 1X carriers)
• BTS always transmits at maximum available power
• Each user receives data from only one base station at a time (no forward link
soft handoff)
• 1xEV-DO lets each user use 100% of available resources, while dynamically
allocating time resources among users for maximum efficiency
• 1xEV-DO uses time-division multiplexing of users on forward link (slots
assigned for
packet transmission)
• Forward link supports higher order modulation (QPSK, 8-PSK and 16-QAM)
• Reverse link (1xEV-DO Revision A) supports higher order modulation
(8-PSK)
• Mobile supports dynamic channel estimation using measured S/N to set the
highest rate it can decode (uses Data Rate Control channel to communicate
to network access point)
• Mobiles can support Rx diversity for S/N enhancements particularly in multi-
path/fading environments
1X and IS-95A
The type of data connection made at any given time depends on the services
available from the carrier in the given coverage area. If 1X packet services are not
available, the modem connects using circuit-switched data over
IS-95A
technology. The modem automatically selects the fastest connection mode
available when a data call is connecting.
When roaming, the modem does not automatically change connection modes. If
the modem connects using 1X and then roams outside of the packet service area,
the connection is dropped. To resume data communication, a new connection
using IS-95A has to be created. Similarly, an IS-95A call established in one area
does not automatically transition to 1X when the unit enters the 3G coverage
area.