Selection of channel for radio resource control signaling in HSDPA
A Radio Network Controller (RNC) is configured to send Radio Resource Control (RRC) messages to a mobile station using a selected downlink channel. Depending on the mobility rate of the mobile station, the RNC is configured to configure a signaling connection to use either a first downlink channel or a second downlink channel for transmitting the RRC messages. According to one embodiment, the RNC selects a dedicated channel when the mobile station has a high mobility rate, and selects a shared channel when the mobile station has a low mobility rate.
1. A signaling method implemented by a radio network controller, said method comprising:
determining a mobility rate of a mobile station;
selecting, when the mobility rate is low, a shared high speed downlink channel for sending both user data and in-band signaling of radio resource control messages on the same channel;
selecting, when the mobility rate is high, a dedicated downlink channel for sending the radio resource control messages while using the shared high speed downlink channel for sending the user data; and
configuring the signaling connection with the mobile station to use the selected downlink channel.
2. The signaling method of claim 1 wherein the mobility rate of the mobile station is determined based on a signal characteristic of the received signal from the mobile station.
3. The signaling method of claim 2 wherein the signal characteristic comprises a Doppler spread of the received signal from the mobile station.
4. The signaling method of claim 3 wherein the radio network controller receives Doppler spread measurements from a serving base station.
5. The signaling method of claim 2 wherein the signal characteristic comprises a signal strength of a received signal from the mobile station.
6. The signaling method of claim 5 wherein the radio network controller receives measurements of the signal strength from a serving base station.
7. The signaling method of claim 1 wherein the mobility rate of the mobile station is determined based on a handover frequency of the mobile station.
8. The signaling method of claim 1 wherein the dedicated channel comprises a Dedicated Physical Channel and wherein the shared channel comprises a High Speed Physical Downlink Shared Channel in a Wideband Code Division Multiple Access system.
9. A radio network controller to control radio resources allocated to a mobile station, said radio network controller comprising:
a control unit configured to:
determine a mobility rate of the mobile station
select, when the mobility rate is low, a shared high speed downlink channel for sending both user data and in-band signaling of radio resource control messages on the same channel;
select, when the mobility rate is high, a dedicated downlink channel for sending the radio resource control messages while using the shared high speed downlink channel for sending the user data; and;
configure the signaling connection with the mobile station to use the selected downlink channel; and
a signaling processor configured to exchange signaling messages with the mobile station over the signaling connection.
10. The radio network controller of claim of claim 9 wherein the mobility rate of the mobile station is determined based on signal characteristics of a received signal from the mobile station.
11. The radio network controller of claim 10 wherein the signal characteristics comprise a Doppler spread of the received signal.
12. The radio network controller of claim 10 wherein the signal characteristics comprise a signal strength of the received signal.
13. The radio network controller of claim 10 wherein the control unit is configured to receive measurements of the signal characteristics from a serving base station.
14. The radio network controller of claim 9 wherein the mobility rate of the mobile station is determined based on a handover frequency of the mobile station.
15. A computer readable medium storing code for controlling a radio network controller, said code including:
code for determining a mobility rate of a mobile station
code for selecting, when the mobility rate is low, a shared high speed downlink channel for sending both user data and in-band signaling of radio resource control messages on the same channel;
code for selecting, when the mobility rate is high, a dedicated downlink channel for sending the radio resource control messages while using the shared high speed downlink channel for sending the user data; and;
code for configuring the signaling connection with the mobile station to use the selected downlink channel.
16. The computer readable medium of claim 15 wherein the code for determining a mobility rate of a mobile station analyzes a signal characteristic of a received signal from the mobile station.
17. The computer readable medium of claim 16 wherein the code for determining a mobility rate of a mobile station determines the mobility rate based on the signal strength of the received signal.
18. The computer readable medium of claim 16 wherein the code for determining a mobility rate of a mobile station determines the mobility rate based on the Doppler spread of the received signal.
19. The computer readable medium of claim 15 wherein the code for determining a mobility rate of a mobile station determines the mobility rate based on handover frequency.