WO2006137005A1

WO2006137005A1 - Method and apparatus for semi-duplex communication in wireless communication system

Info

Publication number: WO2006137005A1
Application number: PCT/IB2006/051969
Authority: WO
Inventors: Ni Ma; Xiaobo Zhang
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2005-06-24
Filing date: 2006-06-20
Publication date: 2006-12-28

Abstract

This invention disclosure proposes a semi-duplex communication method and apparatus with automatic state- switching mechanism for UE. This communication method comprises: detecting whether input information is voice information or not; if so, transmitting the voice information to another UE via a traffic channel; if not, judging whether user's speaking is finished or not; if so, transmitting a state- switching command to another UE via the traffic channel so as to receive the voice information from another UE. The method and apparatus as proposed in the present invention, using automatic state- switching mechanism to replace the current hard push action with special button, can automatically realize semi-duplex communication in wireless communication system.

Description

METHOD AND APPARATUS FOR SEMI-DUPLEX COMMUNICATION IN WIRELESS COMMUNICATION SYSTEM

FIELD OF THE INVENTION The present invention relates to a method and apparatus for communicating in wireless communication system, and more particularly, to a method and apparatus for semi-duplex communication.

BACKGROUND OF THE INVENTION In cellular communication systems, one user equipment (UE) usually communicates with another UE in full-duplex mode, which may simultaneously receive and transmit traffic data.

Fig.l illustrates the scheme of full duplex communication in UP- Base Station -DOWN mode. As shown in Fig.l, two User Equipments (UE), UEl and UE2, utilize Radio Access Network (RAN) as a relay station to exchange information. There are uplink

(UL) control channel and downlink (DL) control channel transferring signaling between each UE and RAN. In addition, two dedicated physical channels (DPCH) are established between them so as to simultaneously transfer traffic data, such as voice signal, in bi-direction. Beside the conventional cellular communication mode as shown in Fig.l, a peer-to-peer (P2P) communication mode, which can save up to 50% radio resource, is proposed recently. Fig.2 shows the scheme of a full duplex P2P communication mode. Referring to the P2P communication mode as shown in Fig.2, two dedicated physical channels are established to communicate directly between two UEs, so as to transfer traffic data in bi-direction. UL control channel and DL control channel are reserved between RAN and UE, so RAN may monitor and manage the P2P communication.

From Fig.l and Fig.2, it is can be seen that in order to realize full duplex communication, two dedicated physical channels need to be allocated to the communicating UEs so as to simultaneously receive and transmit traffic data, no matter in UP- Base Station -DOWN communication mode or P2P communication mode

However, in practical calling process, the two communicating sides usually speak alternately and the speaking-listening state is alternating. It is rare that two sides speak at the same time. As a result, during the whole calling process, only one directional DPCH usually is used to transfer traffic data, which cannot make use of the radio resource sufficiently.

Due to above reason, semi-duplex communication mode is proposed. In Semi-duplex communication mode, there will be only one bidirectional wireless channel bearing traffic data between the two communicating sides. Therefore during Semi-duplex communication only one side is allowed to transmit voice information via wireless channel, which is called speaking sate. Another side may only receive voice information via this wireless channel at the same time, which is called listening state. Accordingly, the only thing needs to be confirmed is which side is in speaking state during a certain period, i.e. owning speaking authority. And speaking-listening states can be switched during the calling process. Thus, semi-duplex communication can be realized and radio resource can be saved.

A kind of wireless communication device, which can realize Semi-duplex communication, is a walkie-talkie used for short-range distance communication. Fig.3 is a flowchart illustrating the Semi-duplex communication between walkie-talkies. As shown in Fig.3, walkie-talkies have a special button, with which user can implement speaking-listening state switching. In detail, when user pushes down the special button, the walkie-talkie enters into speaking state and transmits voice information to others (another side, closed-group, or other users in Ad-hoc group), which are in listening state. Once the speaking finished, the user releases the special button and that walkie-talkie enters into listening state. Then the walkie-talkie transmits a state- switching command to others so as to release the speaking authority, which allowing other users to transmit voice signal via the wireless channel. In listening state, the walkie-talkie can only receive voice information via the wireless channel. According to the flowchart shown in Fig.3, user switch between speaking and listening states by pushing down or releasing the special button. Therefore Semi-duplex communication is realized in short-range distance.

Recently, UE with Push to Talk function (PTT) is introduced. User equipment with PTT function can directly implement Semi-duplex communication with other UEs without dialing the number. Fig.4 is a flowchart illustrating the UE with PTT function realizing semi-duplex communication. As shown in Fig.4, similar with walkie-talkie, UE with PTT function (UEl) has a special button for speaking-listening state switching. When the button is pushed, UE enters into speaking state and transmits voice information to other UEs (such as UE2) via the relay of a RAN. When talking finished, this special button is released. The UE enters into listening state and transmits a state- switching command to other UEs so as to release the speaking authority. It is similar with walkie-talkie that when UE enters into listening state, it can only receive voice information via the relay of a RAN. Shown as Fig.4, UE with PTT function can realize Semi-duplex communication via the relay of a RAN in long-range distance.

From Fig.3 and Fig.4, walkie-talkie and UE with PTT function both switch the speaking-listening states by detecting whether the special button has been pushed. This kind of switching is realized by the user's operation on the special button. It is not so convenient for users to some extend and the calling may be interrupted due to the user's error operation.

Therefore, a new method and apparatus for semi-duplex communication need to be proposed. Thus users do not need to operate the button during calling process and the speaking-listening states can be switched automatically.

OBJECT AND SUMMARY OF THE INVENTION

An object of the present invention is to provide a method and apparatus for semi-duplex communication, with which semi-duplex communication with automatic state- switching mechanism can be realized both in UP- Base Station -DOWN communication mode and P2P communication mode.

Another object of the present invention is to provide a method and apparatus for semi-duplex communication in wireless communication system, with which automatic speaking-listening state switching can be implemented without the user's operation so as to realize semi-duplex communication.

The third object of the present invention is to provide a method and apparatus for direct multicast communications, with which automatic speaking-listening state switching can be realized without the user's manual operation.

According to one aspect of the present invention, a method for wireless communication system is provided to fulfill above objects. The method comprises steps: detecting whether the input information is voice information; if voice information is detected, transmitting the voice information to another UE via a traffic channel; if not, judging whether user speaking is finished; if finished, transmitting a state- switching command to another UE via the traffic channel so as to receive voice information from another UE.

According to another aspect of present invention, user equipment for wireless communication is provided to fulfill above objects. The user equipment comprises: an input apparatus, for receiving voice information; a detecting apparatus, for judging whether the input information is voice information or not; a judging apparatus, for judging whether the user has finished speaking or not according to the detecting result; a transmitting apparatus, for transmitting voice information to another UE via a traffic channel when voice information is detected and transmitting state- switching command to another UE via the traffic channel when user's speaking is finished; a receiving apparatus, for receiving voice information and state- switching command from another UE.

Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Present invention will be explained with detailed examples in conjunction with accompanying drawings, wherein:

Fig.l is a schematic diagram showing the full-duplex UP- Base Station -DOWN communication mode;

Fig.2 is a schematic diagram showing the full-duplex P2P communication mode;

Fig.3 is a flowchart illustrating the Semi-duplex communication between walkie-talkies;

Fig.4 is a flowchart illustrating the Semi-duplex communication between UEs with PTT function;

Fig.5 is a state-chart illustrating the speaking-listening state transfer of a UE according to present invention;

Fig.6 is a flowchart illustrating the Semi-duplex communication realized by automatic state- switching mechanism in UP- Base Station -DOWN communication mode proposed as an embodiment of present invention;

Fig.7 is a block diagram illustrating the judgment of whether the input signal is voice or not by detecting the power of input signal according to an embodiment of present invention;

Fig.8 is a flowchart illustrating the judgment of whether the input signal is voice or not by pitch detection according to an embodiment of present invention;

Fig.9 is the block diagram illustrating the judgment of whether the input signal is voice or not by joint detection of power detection and pitch detection according to an embodiment of present invention;

Fig.10 is a flowchart illustrating the realization of semi-duplex communication using automatic state- switching mechanism in P2P communication mode according to another embodiment of present invention;

Fig.11 illustrates the transfer procedure of synchronization shift command and transmission power control command in full-duplex P2P communication mode;

Fig.12 illustrates the transfer procedure of synchronization shift command and transmission power control command in semi-duplex P2P communication according to present invention;

Fig.13 is a flowchart illustrating the processing of inserted voice by buffering voice data in semi-duplex UP- Base Station -DOWN communication according to another embodiment of present invention;

Fig.14 is a flowchart illustrating the processing of inserted voice by RAN-assisted state- switching mechanism in semi-duplex P2P communication according to another embodiment of present invention;

Fig.15 is a schematic diagram showing the existing direct multicast communication;

Fig.16 is a flowchart illustrating the realization of multicast communication using automatic state- switching mechanism according to another embodiment of present invention;

Fig.17 is a schematic diagram showing the realization of semi-duplex communication using automatic state- switching mechanism according to another embodiment of present invention.

Throughout the drawing figures, like reference numerals will be understood to refer to like parts and components.

DETAILED DESCRIPTION OF THE INVENTION

According to the semi-duplex communication method as proposed in the present invention, UE can automatically judge if the speaking-listening state switching is need by detecting whether the input signal from a receiver is voice signal. Fig.5 is a state-chart illustrating the speaking-listening state transfer of the UE according to present invention. As shown in Fig.5, when UE is in speaking state, further if the detected input signal is non-voice signal and the duration of the non-voice signal is greater than a predefined threshold, the UE will transmit state-switching command to other UEs which are in listening state so as to release speaking authority and this UE switches from speaking state to listening state. When UE is in listening state, it can be switched to speaking state by receiving the state- switching command from other UEs so as to get speaking authority.

By utilizing the semi-duplex communication method with automatic state switching mechanism as proposed in the present invention, it is convenient to realize semi-duplex communication for current cellular communication system. Not only the radio resource can be utilized adequately, but also the operation of the special button is not needed. Thus the calling procedure becomes natural and smooth.

First, taking UP- Base Station -DOWN communication mode as example, we will describe in detail with the attached figures how the proposed semi-duplex communication method detects the input signal as voice signal, how to judge whether the state- switching is needed based on the detection result of input signal, and the transfer procedure of voice information in speaking and listening states.

Fig.6 is a flowchart illustrating the Semi-duplex communication method in UP- Base Station -DOWN communication mode as proposed in the present invention.

As shown in Fig.6, for realizing semi-duplex communication in UP- Base Station -DOWN communication mode, besides UL control channel and DL control channel should be unchanged between UE (UEl or UE2) and RAN, only one dedicated physical channel (DPCH) need be established to realize the bidirectional traffic transmission.

In the embodiment shown in Fig.6, it is supposed that the calling UE (for instance UEl) enters into speaking state initially, i.e. owning speaking authority first, while the called UE2 is initialized in listening state. Of course, according to a predefined rule, the called UE (for instance UE2) can also be initialized in speaking state.

As shown in Fig.6, in speaking state, UEl will detect whether the input signal from the receiver is voice signal or not continuously (Step S610). The detailed detection method will be described thoroughly in Fig.7 and Fig.8.

If the detecting result of step S610 shows that the input signal from the receiver is voice signal, then UEl can transmit voice information to UE2. In detail, UEl transmits the voice information and identifier information (for instance phone number) of the receiving side (UE2) to RAN (Step S630) via the DPCH allocated to UEl. Then, RAN transmits the voice information from UEl to the UE identified by the identifier information of the receiving side, such as UE2 (Step S640). If the voice signal is detected continuously in step S610, the voice information can be continuously transmitted to UE2 via the relay station of RAN.

If the detecting result of step S610 shows that the input signal is non-voice signal, then it may further judge whether the user's speaking is finished or not (Step S620).

More specifically, when non-voice signal is detected in step S610, a timer T_M is started (Step S621) to count the duration of the non-voice signal. During the counting procedure of the non-voice signal duration, it needs to continuously judge whether T_M has expired a predefined threshold T₀ (Step S623) which indicates that the speaking is finished. If T_M ≤ T₀, the detection of whether the input signal from the receiver is voice signal should be continued (Step S625), in which the detection method is same as step S610. If the detection result of step S625 is voice signal, it indicates that the user is still speaking. At this time, timer T_M will be set to zero and stop counting (Step S627), while the flow goes back to step S610. And the detection of input signals from the receiver is kept on so as to transmit voice signal to UE2 via the relay station of RAN.

Otherwise, if the detection result of step S625 is non-voice signal, it indicates that the duration of non-voice signal is still extending. Timer T_M continues to count and flow goes back to step S623. When the detected duration T_M of non-voice signal is greater than the threshold T₀, it indicates that user has finished speaking, i.e. speaking state is end.

When it is determined that user's speaking is finished in step S620, UEl will transmit state- switching command to UE2 via DPCH at the end of voice information being sent, so as to release speaking authority (Step S650). Then, UEl enters into listening state, that is to say, UEl can only receive the information from DPCH.

Next, UE2, which is in listening state, enters into speaking state immediately after receiving the state- switching command from RAN (Step S660). Here, UE2 can do the operations same as UEl does in speaking state, i.e. if voice signal is detected, the voice signal will be transmitted to UEl via the relay station of RAN; if it is detected and determined that the user finished speaking, the state-switching command will be transmitted to UEl via RAN, so as to release speaking authority and speaking state is switched back to listening state.

Detection of Voice Signal In Semi-duplex communication procedure shown in Fig.6, the detection of input signal (Step S610) can be realized with various methods. Power Detection and Pitch Detection are illustrated in Fig.7 and Fig.8 respectively.

Power Detection Method

According to the characteristics of human speech, voice signal and non-voice signal have different power levels generally, as shown in Fig.7. Obviously, a voice signal has higher power than non- voice signal. This characteristic can be used to judge whether the input signal is voice signal according to the power of input signal. More specifically, a voice power threshold Po can be predefined, which could be predefined according to practical environment measuring result and updated based on the changes of the environment. Then, UE calculates the input signals' average power P_M of a signal-processing interval, which is designated by the system, e.g. 5ms, 10ms, etc, from the receiver. If the P_M < Po, the input signals will be regarded as a non-voice signal, otherwise the input signals will be regarded as voice signals. As shown in Fig.7, when the duration of detected non-voice signal T_M > To, step S620 determines that the user's speaking is finished.

Pitch Detection Method

Another method can be used to detect the input signal is based on the pitch pattern. People always pronounce sonant syllables during their speaking, and there is a definite interval between the two consecutive sonant pronunciations. This interval is not greater than the maximum interval T_v between the two consecutive sonant signals. According to this characteristic, whether the input signal is voice signal can be judged by detecting the sonant signal of input signal and the interval between sonant signals.

One of the sonant syllables' characteristics is that peak power can be found at a certain frequency and its harmonic frequency. This frequency is called pitch frequency. Therefore, we can judge whether the signal is sonant signal or not by detecting whether pitch exists in the signals. And the voice signal can be judged further.

Fig.8 illustrates the method based on pitch detection. As shown in Fig.8, when the input signal is received from receiver (Step S810), the first thing is to detect whether the input signal is sonant signal (Step S820). If the detection result indicates the input signal is non-sonant signal, a timer Ti will be started to count the duration of non-sonant signal (Step S830). Then, it continues to detect whether the input signal is sonant signal (Step S840). If non-sonant signal is detected continuously and the duration of non-sonant signal Ti is greater than the threshold T_v (Step S850), it indicates that the input signal is non-voice signal. Otherwise, if the input signal is detected as sonant signal in step S820 and S840, it indicates that the input signal is voice signal and Ti is set to zero until next non- sonant signal is detected and timer restart counting (Step S860).

Step S 820, shown in Fig.8, can adopt several existing pitch detection methods to detect whether the input signal is sonant signal. For example, time domain autocorrelation and frequency domain down sampling algorithm are the typical detection methods. Among them, for time domain autocorrelation algorithm, if the time domain autocorrelation function of input signal is a periodical function and has a pitch period interval, it indicates the input signal is sonant signal; otherwise the input signal is non-sonant signal. Frequency domain down sampling algorithm utilizes the characteristic that peak power can be found at pitch frequency and its harmonic frequency. If the input signal is down sampled with different compressing factors, multiple compressed spectra signals can be obtained. Then, all the signals are added together to combine one signal. If the combined signal still has an obvious peak power at pitch frequency, it indicates that the input signal is sonant signal; otherwise the input signal is non- sonant signal.

Joint detection of Power Detection and Pitch Detection

Above, two detection methods, i.e. power detection and pitch detection are introduced respectively in conjunction with Fig.7 and Fig.8. In practical applications, if user's voice is very low and environment noise is very big, or detection threshold (such as power threshold Po, or maximum sonant interval T_v) is not chosen properly, any of the detection methods being used alone will possibly bring about unexpected detection failure.

In order to increase the reliability of voice detection, two detection methods mentioned above can be jointly used as shown in Fig.9. In Fig.9, the input receiver's signal is transferred to the power detection unit 700 and pitch detection unit 800 in joint detection unit 900 separately. Then the detection results of these two detection units are transferred to AND operation unit 900 for combining. If the detection results of these two detection units are all voice signals, then the input signal is confirmed as voice signal. If any one of the detection results is non-voice signal, then the input signal is confirmed as non-voice signal.

Therefore, according to the detection method and apparatus as proposed in Fig7 ~ Fig.9, detecting whether the input receiver's signal is voice signal, UE can automatically judge whether user has finished speaking as shown in Fig.6. Consequently, it can be confirmed that whether transmitting state- switching command is needed so as to realize the automatic switching of speaking-listening states. Adopting the method shown in Fig.6 to implement semi-duplex communication, UE needn't be provided with special hard push button, and the calling procedure is automatically performed without user's intervention, in other words, the semi-duplex communication can be realized automatically.

Above contents describe the realization of semi-duplex UP- Base Station -DOWN communication procedure with Fig.6. Of course, present invention is not limited to the UP- Base Station -DOWN communication mode. It can also be applied in P2P communication mode. Fig.10 illustrates the application of semi-duplex communication method in P2P communication mode according to present invention.

As shown in Fig.10, for realizing semi-duplex P2P communication, only one DPCH, which bears traffic data, needs to be established between two UEs. The link of control channel is still being kept between each UE and RAN at the same time. In this embodiment, it is supposed that UEl is initialized in speaking state.

As shown in Fig.10, in speaking state, UEl firstly detects whether input receiver's signal is voice signal (Step S610) according to above-mentioned voice detection methods. If the detection result is voice signal, then UEl may transmit voice information to UE2 via DPCH allocated for directly communicating with UE2 (S 1030). If the detection result of step S610 is non-voice signal, it need further judging whether user's speaking is finished according to the same method shown in Fig.6 (Step S620). If user's speaking is not finished, then it goes back to step S610 and continuously detects the input signal. If step S620 determines that user's speaking is finished, then UEl will transmit state- switching command to UE2 via DPCH at the end of transmitted voice information, so as to release speaking authority (Step S 1050). At this time, UEl enters into listening state, and can only receive voice information from UE2 via DPCH. Once UE2, which is in listening state, receives the state- switching command, it enters into speaking state. Here, UE2 can perform the same operation as UEl in speaking state. Thus, two UEs, adopting P2P communication mode, can realize semi-duplex communication on the allocated DPCH.

It should be noted here, in full duplex P2P communication mode, two UEs could implement close-loop transmission synchronization and power control via the allocated two DPCHs. Fig.11 illustrates the close-loop control procedure. As shown in the figure, when UE2 receives the traffic data from UEl via DPCHl, the synchronization shift (SS) command and transmission power control (TPC) command, which are used for adjusting transmission synchronization and transmission power of UEl, can be transmitted to UEl via DPCH2, so that UEl can do proper adjustment according to the received commands. Whereas, as shown in Fig.10, in semi-duplex P2P communication, since UE2, which in listening state, does not occupy DPCH, UEl, which in speaking state, can not get TPC and SS commands from UE2. This may result in communication failure.

Accordingly, present invention proposes that the transmission of TPC and SS commands between two UE can be realized via relay station of RAN in semi-duplex P2P communication, shown as in Fig.12. In Fig.12, when UE2 in listening state continuously receives the voice information from UEl via DPCH, UE2 detects the transmission synchronization and transmission power of UEl according to the received data (Step S1220). If the transmission synchronization and transmission power of UEl needs to be adjusted by detecting (Step S 1230), then UE2 transmits TPC and SS commands to RAN (Step S 1240) via UL control channel, for instance, physical random access channel (PRACH). And then, RAN transmits TPC and SS commands from UE2 to UEl (Step S 1250) via DL control channel, for instance, secondary common control physical channel (S-CCPCH). UEl adjusts transmission power and synchronization according to the received TPC and SS commands from RAN (Step S 1260), and then transmits voice information to UE2 via DPCH using the adjusted transmission power and synchronization (Step S1270).

Therefore, the proper working of the Semi-duplex P2P communication can be ensured, if the semi-duplex P2P communication shown in Fig.10 adopts the transfer method of TPC and SS command shown in Fig.12.

Above contents describe the application of semi-duplex communication method with automatic state- switching mechanism in semi-duplex UP- Base Station -DOWN communication mode and P2P communication mode as proposed in the present invention. Whereas, for the above description, only the common communication situation is considered, in which two communication sides speak alternatively. And the special case, that is, the user needs to insert voice when being in listening state is not considered. Following contents will describe the solution for the voice information transmission under inserting voice situation using semi-duplex communication method as proposed in the present invention. Fig.13 is a flowchart illustrating the processing of voice information transmission under inserting voice situation in semi-duplex UP- Base Station -DOWN communication mode. As shown in Fig.13, UE2, which is in listening state, needs to continuously detect whether the input receiver's signal is voice signal (Step S610), during the procedure of receiving the voice information from UEl via relay station of RAN (Step S630 and S640). If user suddenly inserts voice at the moment, voice signal will be detected in step S610. Then, the input voice signal is stored in a temporary buffer unit (Step S 1330). After UE2 has received the state- switching command from UEl via relay station of RAN (Step S650 and S660) and switched to speaking state, UE2 will first transmit the voice information stored in the buffer unit to UEl via relay station of RAN (Step S 1370 and S 1380). If there is no voice information stored in the buffer unit, the input receiver's voice signal will be transmitted. Here, UE2 can automatically allocate buffer unit when voice signal is detected, and automatically release the buffer unit after the voice signal stored in buffer unit has been transmitted. So that memory space can be saved.

The solution for processing the inserted voice in semi-duplex communication as shown in Fig.13 can also be used in semi-duplex P2P communication. When the solution for processing the inserted voice by buffering the voice information is used in semi-duplex P2P communication, the operation of UE in listening state is basically same as the steps shown as in Fig.13. The only difference is that UE2 can directly receive voice information and state- switching command from UEl via DPCH without relay station of RAN.

Besides the inserted voice is processed by buffering, it can also be solved via RAN-assisted state switching. Following will take semi-duplex P2P communication as an example in conjunction with Fig.14 to describe the method for solving the inserted voice via RAN-assisted state switching as proposed in present invention.

As shown in Fig.14, UE2, which is in listening state, directly receive the voice information from UEl via allocated DPCH (Step S 1030). During this procedure, UE2 also needs to continuously detect whether the input receiver's signal is voice signal (Step S610). During listening procedure, if the user inserts voice suddenly, voice signal will be detected in step S610 and the input voice signal will be stored in a temporary buffer unit (Step S1330). Then, occupancy of this buffer unit is judged whether it is greater than a predefined threshold, for instance 80% (Step S 1420). If buffer unit has enough memory space, detecting input signal is continued and the input voice signal can be stored continuously. If the occupancy of buffer unit is greater than 80%, then UE2 transmits state- switching request to RAN via PRACH so as to obtain speaking authority (Step S1430). Then, RAN transmits this state- switching request to UEl via S-CCPCH (Step S1440). When UEl, which is in speaking state, receives this state- switching request, it transmits state- switching command on DPCH at once so as to release speaking authority and switches to listening state automatically (Step S 1450). When UE2 receives state- switching command and enters into speaking state, it transmits the voice information stored in buffer unit to UEl via DPCH (Step S1460). Thus, with the help of RAN, UE2, which is in listening state, may transmit state- switching request to UEl, which is in speaking state. This will break in UEl 's speaking and force UEl releasing speaking authority and switching state.

As shown in Fig.14, RAN-assisted state switching method can also be used in semi-duplex UP- Base Station -DOWN communication. In semi-duplex UP- Base Station -DOWN communication, the operation of RAN-assisted state switching is basically same as in Fig.14. The only difference is that, besides state- switching request need relayed via RAN, voice information and state- switching command are all need relayed via RAN to be transmitted between two UEs. It should be noted that, in semi-duplex UP- Base Station -DOWN communication, in order to avoid frequently state- switching via RAN in situation that two UEs are without input voice signal, UE can only automatically switch state after UE transmits voice signal in speaking state, otherwise it stays in speaking state waiting for the input voice signal. In the situation that UE is in speaking state waiting for the input voice signal, if UE, which is in listening state, need transmit voice information, the speaking authority can be obtained via transmitting state switching request as shown in Fig.14.

Above contents discuss the methods for realizing semi-duplex P2P communication using automatic state switching mechanism. In practical applications, such as during conference call, it is also expected that automatic state switching can be realized in Peer-to-Multi-Peer (P2MP) communication, so that attended user can obtain speaking authority without hardware operation.

Fig.15 is a schematic diagram of P2MP. As shown in the figure, suppose UEl speaks first among three user equipments UEl, UE2 and UE3, i.e. UEl is initialized in speaking state while UE2 and UE3 are in listening state. Thus, RAN allocates DPCH for bearing traffic data to UEl. UEl establishes directional Peer-to-Multi-Peer link with UE2 and UE3 using the allocated DPCH. At this time, UL control channel and DL control channel are still kept between each UE and RAN.

Fig.16 illustrates the realization of automatic state switching in P2MP communication. As shown in Fig.16, when UEl, which is in speaking state, detects the input receiver's signal is voice signal (Step S610), it transmits the voice information to UE2 and UE3 via allocated DPCH for P2MP communication (Step S1610). If UEl detects non-voice signal and determines that user's speaking is finished (Step S620), UEl transmits state- switching command to UE2 and UE3 via DPCH so as to release speaking authority (Step S 1620). Here, if UE2 or UE3, which is in listening state, detects the input receiver's signal is voice signal (Step S610a and S610b), it transmits state-switching request to RAN via UL control channel (PRACH) (Step S1630a and S1630b). When RAN receives state- switching request from UE2 or UE3, according to predefined network strategy, competitive mechanism and QoS request, RAN confirms which UE can obtain speaking authority and occupy DPCH for P2MP communication (Step S 1640). After confirming the UE who can own speaking authority (for instance UE2), RAN will allocate DPCH to this UE. So, UE2 enters into speaking state (Step S 1650).

Above contents describes thoroughly the methods for realizing semi-duplex communication using automatic state switching mechanism in conjunction with accompanying drawings as proposed in present invention. The methods as proposed in present invention not only can be used in TDD system, but also be used in FDD system. Furthermore, the methods as proposed in present invention can be realized with software, or hardware, or combination of them.

Fig.17 illustrates the block diagram of a UE for performing semi-duplex communication using automatic state- switching mechanism according to one embodiment of present invention. The elements same as traditional UE are not shown in Fig.17.

As shown in Fig.17, the UE according to one embodiment of present invention comprises: a receiver 1710, for receiving user's voice signal; a detecting unit 1720, for detecting whether the input signal of receiver 1710 is voice signal; a judging unit 1730 judging whether the user has finished speaking according to the detection result from detecting unit 1720. If the duration of non-voice signal detected by detecting unit 1720 is greater than a predefined threshold, it can determine that the user has finished speaking; a transmitting unit 1740 for transmitting voice signal via traffic channel when detecting unit 1720 detects the input signal is voice signal, or transmitting a state- switching command via traffic channel when judging unit 1730 determines the user has finished speaking; and a receiving unit for receiving voice information from the network and another UE via traffic channel, and state-switching command from another UE.

Preferably, the UE further comprises a buffer unit 1760 for buffering voice information detected by detecting unit 1720, i.e. vice information suddenly inserted by the user when the UE is in listening state. When receiving unit 1750 receives a state- switching command, transmitting unit 1740 will firstly transmit the voice information stored in buffer unit 1760.

Preferably, when the occupancy of buffer unit 1760 is greater than a threshold, transmitting unit 1740 can transmit a state-switching request to RAN via UL control channel. Receiving unit 1750 can receive a state-switching request from RAN via DL control channel. Then, transmitting unit 1740 transmits a state- switching command to the network and another UE via traffic channel according to the state- switching request.

Preferably, if UE has P2P communication capability, transmitting unit 1740 may also transmit TPC and SS commands to RAN for adjusting the peer UE via UL control channel. Receiving unit 1750 may receive TPC and SS commands of the peer UE from RAN via DL control channel.

Advantageous Effects of the Invention

With regard to the detailed description of the present invention taken in conjunction with accompanying drawings, when adopting the semi-duplex communication method with automatic state- switching mechanism as proposed in the present invention, semi-duplex communication can be realized in UP- Base Station -DOWN communication system and P2P communication system. Accordingly, radio resource of conventional cellular systems can be saved, and radio resource of P2P communication can be reduced further.

At the same time, since semi-duplex communication can be realized in cellular system when adopting the method as proposed in the present invention, the UE power consumption can be reduced. For example, when semi-duplex communication is realized in FDD system, UE can turn on transmitting unit and receiving unit alternatively. That is, transmitting unit is turned off when receiving voice data, while receiving unit is turned off when transmitting voice data. Therefore, the UE power consumption can be reduced in semi-duplex mode comparing with full-duplex mode, in which the transmitting unit and receiving unit must be turned on simultaneously. Taking another example, when adopting semi-duplex communication in TDD system, only one DPCH can be assigned to each UE in voice dialogue. Thus UE only turns on the transmitting unit or receiving unit allocated on this DPCH, while transmitting unit and receiving unit on two DPCH must be turned on in full-duplex mode. Consequently, the UE power consumption can be reduced.

In addition, since only one UE is transmitting voice information in a certain period when adopting semi-duplex communication, the interference between the users can be reduced in the system.

Furthermore, in the semi-duplex communication method as proposed in the present invention, automatic state- switching mechanism replaces the hard push action with special button in the current semi-duplex system. Accordingly, the UE intervention may be avoided for communication procedure and it is convenient for user's operation.

It is to be understood by those skilled in the art that the method and apparatus for semi-duplex communication with automatic state- switching mechanism as disclosed in this invention can be made of various modifications without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

CLAIMS:

1> A communication method performed by a user equipment (UE) in a wireless communication system, comprising the steps of:

(a) detecting whether input information is voice information;

(b) transmitting voice information to another UE via a traffic channel, if the voice information is detected;

(c) judging whether user's speaking is finished, if non-voice information is detected; and

(d) transmitting state- switching command to another UE via said traffic channel, if user's speaking is finished, so as to receive voice information from said another UE.

2Λ The method according to claim 1, wherein said step (c) further comprising: judging whether the duration of detected non-voice information is longer than a predefined threshold, if so, determining that user speaking is finished.

3Λ The method according to claim 2, further comprising: receiving a state- switching request from said another UE via downlink control channel; and transmitting said state- switching command to said another UE via said traffic channel, so as to receive voice information from said another UE.

4Λ The method according to claim 3,, wherein said downlink control channel is secondary common control physical channel (S-CCPCH).

5Λ The method according to claim 2, further comprising:

(e) receiving voice information from said another UE via said traffic channel;

(f) receiving state- switching command from said another UE via said traffic channel; and (g) transmitting voice information via said traffic channel.

6Λ The method according to claim 5, further comprising steps before step (f):

(el) detecting whether said input information is voice information when receiving voice information from said another UE; and

(e2) if voice information is detected, buffering detected voice information in a buffer.

7Λ The method according to claim 6, further comprising:

(e3) transmitting said state- switching request to the network via uplink control channel.

8Λ The method according to claim 6 or 7, further comprising:

(h) transmitting said buffered voice information to said another UE via said traffic channel.

9Λ The method according to claim 8, wherein said uplink control channel is Physical

Random Access Channel (PRACH).

ICK The method according to any one of claims 1 to 9, wherein said UE has Peer-to-Peer(P2P) communication capability and said traffic channel is a direct traffic channel between said UE and said another UE.

IK The method according to claim 10, further comprising: transmitting transmission power control command and synchronization shift command to the network via said uplink control channel so as to adjust transmission power and synchronization of said another UE.

12Λ The method according to claim 10, further comprising: receiving transmission power control command and synchronization shift command from the network via said downlink control channel so as to adjust transmission power and synchronization of said UE.

13 Λ The method according to claim 7, wherein said UE has capability of Peer-to-Multipeer (P2MP) communication and said traffic channel is direct P2MP traffic channel established between said UE and a plurality of another UEs.

14Λ The method according to claim 13, further comprising:

(i) detecting whether said input information of input unit is voice information;

(j) If voice information is detected, transmitting said state- switching request to the network via said uplink control channel.

15 Λ The method according to claim 1 or 6, wherein said step of detecting whether said input information is voice information comprises:

(Al) detecting whether average power of said input information is greater than a predefined threshold so as to judge whether said input information is voice information.

16Λ The method according to claim 1 or 6, wherein said step of detecting whether said input information is voice information comprises:

(A21) detecting whether said input information is sonant information so as to judge whether said input information is voice information;

(A22) If said input information is detected as non- sonant information, detecting whether duration of said non-sonant information is greater than a predefined threshold; and

(A23) If said input information is detected as non-sonant information, and the duration of said non-sonant information is greater than said predefined threshold, determining that said input information is non- voice information.

17Λ The method according to claim 16, wherein step (A21) comprises one of the following steps of: detecting whether said input information is sonant information, according to pitch detecting method of said input information's auto-correlation function in time domain; adopting pitch detecting method with frequency domain pitch down sampling to detect whether said input information is sonant information.

18Λ The method according to claim 1 or 6, wherein said step of detecting whether the input information is voice information comprises:

(A3) If the average power of said input information is lower than a predefined threshold, or said input information is detected as non- sonant information and the duration of non- sonant information is greater than a predefined threshold, determining that said input information is non- voice information.

19Λ A UE for wireless communication system, comprising: an input unit, for receiving voice information; a detecting unit, for detecting whether input information from said input unit is voice information; a judging unit, for judging whether user speaking is finished according to the detecting result of said detecting unit; a transmitting unit, for transmitting voice information to another UE via a traffic channel when said detecting unit detects voice information, and transmitting state- switching command to said another UE via a traffic channel when said judging unit judges that user speaking is finished; a receiving unit, for receiving voice information and state- switching command from said another UE.

20Λ The UE according to claim 19, wherein said judging unit judges whether duration of non-voice information is greater than a predefined threshold, if so, determining that user speaking is finished. 21 Λ The UE according to claim 20, wherein said receiving unit receives a state- switching request from said another UE via downlink control channel, and said transmitting unit transmits said state- switching command to said another UE via said traffic channel according to said state- switching request received from said receiving unit, so as to receive voice information from said another UE.

22Λ The UE according to claim 20, further comprising: a buffering unit, for buffering detected voice information when said receiving unit receives said voice information from said another UE and said detecting unit detects said voice information.

23 Λ The UE according to claim 22, wherein said transmitting unit transmits a state-switching request via uplink control channel.

24 Λ The UE according to claim 20 or 23, wherein said transmitting unit transmits said buffered voice information to said another UE via said traffic channel.

25 Λ The UE according to any one of claims 19 to 24, wherein said UE has P2P communication capability, and said traffic channel is direct traffic channel between said UE and said another UE.

26 Λ The UE according to claim 25, wherein said transmitting unit transmits transmission power control command and synchronization shift command via said uplink control channel so as to adjust transmission power and synchronization of said another UE.

27Λ The UE according to claim 25, wherein said receiving unit receives transmission power control command and synchronization shift command from said another UE via said downlink control channel, so as to adjust transmission power and synchronization of said UE.

28Λ The UE according to claim 19, wherein said detecting unit comprises: a power detecting unit, for detecting whether average power of said input information is higher than a predefined threshold, if the average power of said input information is higher than said threshold, said input information is judged as voice information.

29Λ The UE according to claim 19, wherein said detecting unit comprises: a pitch detecting unit, for detecting whether said input information is sonant information; if sonant information is detected, then said input information is judged as voice information; and if said input information is detected as non- sonant information and the duration of non-sonant information is greater than a predefined threshold, said input information is judged as non- voice information.

3CK The UE according to claim 19, wherein said detecting unit comprises: a power detecting unit, for detecting whether average power of said input information is higher than a predefined threshold; a pitch detecting unit, for detecting whether said input information is sonant information and the duration of detected non- sonant information is greater than another predefined threshold; and a AND operation unit, for judging that said input information is non-voice information when said power detecting unit detects the average power of said input information is lower than said predefined threshold, or said pitch detecting unit detects that said input information is non-sonant information and the duration of non-sonant information is greater than said another predefined threshold.