Telefonaktiebolaget Lm Ericsson (publ)

Sylvain St-Pierre

Francois Sawyer

Eric Turcotte

Francis Lupien

Sylvain Labonte

A D-AMPS+ cellular communications air interface is presented wherein a packet data control channel and packet data traffic channel is supported in addition to the conventional digital control channel and digital traffic channel. In particular, the packet data control channel, packet data traffic channel and digital traffic channel support multiple modulation level operation (high versus low). Procedures are provided for intracell and intercell modulation transition of mobile station communications carried by a traffic channel. In particular, these procedures facilitate intracell and intercell modulation transition to a traffic channel using the same level of modulation, as well as intracell and intercell (fall-forward and fall-backward) modulation transition to a traffic channel using a different level of modulation.

Support of multiple modulation levels for a cellular traffic channel

During a 'make before you break' handoff performed within a CDMA communications system, duplicate downlink communications are generated and routed through different base stations for delivery to the mobile station. At the mobile station, the duplicate signals are received and the frame sequence numbers of the substantially simultaneously received frames therein are compared. If the sequence numbers do not match, the duplicate signals are identified as not being synchronously received by the mobile station. In response thereto, the mobile station signals the communications network on the uplink with a timing adjustment message, and appropriate timing modifications are made with respect to the transmission of the duplicate signals in order to provide for substantially synchronous reception. Diversity combination and decoding are then performed on the received signals. Alternatively, the mobile station buffers the earlier arriving signal and waits for the later arrival of the sequence number matching frame of the duplicate signal before engaging in diversity combining and decoding of the received signals.

Growing community of inventors

St-Lazare, Canada

Sylvain St-Pierre