Method of idle mode control in OFDM system

• US 20050099988A1
• Filed: 11/05/2004
• Published: 05/12/2005
• Est. Priority Date: 11/07/2003
• Status: Active Grant

• Current Assignee: Alcatel SA (Nokia Corporation)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Wang, Yang, Wan, Yan
• Granted Patent: US 7,583,624 B2
• Time in Patent Office: Days
• US Class Current: 370/343
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

The present invention discloses a method of idle mode control in an orthogonal frequency-division multiplexing (OFDM) system. By superposing idle mode control channels on a frame synchronization pattern in the frame header of an OFDM frame, mobile terminals at a low migration rate will be switched into idle mode during packet service transmission intermission period. The mobile terminals in idle mode needn'"'"'t do FFT to check whether there is any packet to be received after receiving every frame, thereby the power energy of the mobile terminals is greatly saved.

Claims

1. A method of idle mode control in an orthogonal frequency-division multiplexing system, characterized in that said method comprises the steps of:

a) Access Point (AP) superposing m idle mode control channels on a frame synchronization pattern of an orthogonal frequency-division multiplexing (OFDM) frame, m>

=1;

b) the AP transmitting in said idle mode control channels information determining whether a Mobile Terminal (MT) shall enter idle mode or activate mode and sending said frame to a mobile terminal (MT);

c) the MT receiving said frame and entering idle mode or activate mode in accordance with said information in said idle mode control channels;

2. A method as claimed in claim 1, characterized in that said superposing step comprises the steps of:

a1) spreading idle mode control channels by using channelisation codes to obtain idle mode control channels that are orthogonalized each other;

a2) summating all the idle mode control channels that are orthogonalized each other to obtain the summating results;

a3) multiplying frame synchronization patterns transmitted from a frame synchronization pattern generator by the summating results obtained in step a2;

a4) adding the results obtained in step a3 to the frame synchronization patterns to obtain a frame having superposed idle mode control channels on frame synchronization patterns.

3. A method as claimed in claim 2, characterized in that, said idle mode control channels that are orthogonalized each other are allocated by a radio-resource-control (RRC) layer at the AP side in accordance with the system'"'"'s requirements so as to be divided into Idling Channels and Activating Channels shared by all users in a cell.

4. A method as claimed in claim 3, characterized in that, said step for transmitting information determining whether the MT shall enter idle mode or activate mode is to transmit Identification of said MT (MT_ID) in the control channels corresponding to the mode which the MT is to be enter.

5. A method as claimed in claim 4, characterized in that, the MT in activate mode detects all idling channels every time it receives a frame, and if its MT_ID is detected, the MT enters idle mode.

6. A method as claimed in claim 5, characterized in that, the MT in idle mode detects all activating channels every one idle period, and if its MT_ID is detected, the MT leaves the idle mode, demodulate Time-Frequency Units Allocation Channel and does FFT to demodulate packet data under the control of the Time-Frequency Units Allocation Channel;

if its MT_ID is not detected, the MT enters next idle period.

7. A method as claimed in claim 2, characterized in that, each of said idle mode control channels that are orthogonalized each other is allocated an MT_ID by a radio-resource-control (RRC) layer at the AP side in accordance with the system'"'"'s requirements, said MT_ID corresponds to each MT using packet service, i.e., each MT using packet service has a Dedicated Idle Mode Control Channel.

8. A method as claimed in claim 7, characterized in that, said step for transmitting information determining whether the MT shall enter idle mode or activate mode is to transmit the MT'"'"'s idle codes or activate codes in the MT'"'"'s Dedicated Control Channel.

9. A method as claimed in claim 8, characterized in that, the MT in activate mode detects all its Dedicated Idle Mode Control Channels every time it receives a frame, and if idle code is detected, the MT enters idle mode.

10. A method as claimed in claim 9, characterized in that, the MT in idle mode detects its Dedicated Idle Mode Control Channels at the end of each idle period;

if activate code is detected, the MT leaves the idle mode, demodulate Time-Frequency Units Allocation Channel and does FFT to demodulate packet data under the control of the Time-Frequency Units Allocation Channel;

if activate code is not detected, the MT enters next idle period.