Patent Application
20110195674
1. Field of the Invention
The present invention relates to establishing one-way communications over a session initiation protocol (SIP) based network. More specifically, the present invention relates to establishing one-way communication over an SIP-based network without using a push-to-talk (PTT) server by using standard SIP fields.
2. Description of the Related Art
PTT communications are most often used in group communication where groups of three or more users intend to communicate simultaneously amongst each other. Typically, these PTT communications are controlled through the use of a push button on a device that a user presses when he wants to speak. Once this push button is pressed, the device sends a service request to a communications network. The network will then either reject the service request or allocate communication resources to the device based on various criteria, such as priority of the requesting device, what resources are available, etc. If the service request is accepted, a connection will be established between the users of the group so that audio communication between the requesting user and the rest of the group takes place. Then, when the requesting user is finished talking and releases the button, the device will transmit a release message to the network, and the connection will be terminated.
An example of such a PTT system is shown in U.S. Patent Application Publication 2003/0053434. In this system, users are able to communicate with one another through a Push-to-Talk Multicast gateway, as shown in FIG. 1 of U.S. Patent Application Publication 2003/0053434. However, this system is network-centric, relying upon a Wireless Local area network Mobile Radio Service Controller (WLMRSC) to manage the connections between the users. The reliance on a WLMRSC increases the amount of required equipment and the costs of using this PTT system.
Recently systems for performing PTT communications on a one-to-one basis have been proposed. U.S. Pat. No. 7,058,042 teaches an example of such a PTT system. In this system an IP communication service layer is provided over the top of a standard mainstream cellular radio network. This layer relies on a call processing server (CPS) to communicate PTT calls between two separate mobile stations. This system uses the Real-time Transport Protocol (RTP) with embedded signaling to establish one-to-one communications over the cellular radio network. It first sends a leader packet containing the caller's identity information including a special payload number through the network to a receiver. The receiver then responds by sending a positive acknowledgement packet to a communications server in response to receiving the leader packet. If the server does not receive this positive acknowledgment packet it will timeout and send a negative acknowledgement to the caller. However, if the positive acknowledgement packet is received, a connection between the caller and receiver will be initiated. However, this system also relies on a network server, which increases the amount of required equipment and the costs of using this PTT system.
To overcome the problems described above, preferred embodiments of the present invention provide a method and device for establishing a one-way communication session without having to modify existing network and receiver hardware and with reduced costs because a network server, or any other network controlling equipment, is not used.
According to a preferred embodiment of the present invention, a method of establishing a one-way communication session from a first device to a second device includes transmitting initiation data to the second device to establish the one-way communication session transmitting communication data to the second device, and terminating the one-way communication session. The initiation data causes the second device to receive the communication data and prevents the second device from transmitting communication data to the first device until after the one-way communication session has been terminated.
The method preferably further includes waiting to receive a first acknowledgement message from the second device after transmitting the initiation data. The communication data is preferably transmitted after receiving the first acknowledgement message. The method preferably further includes transmitting a second acknowledgement message from the first device to the second device after receiving the first acknowledgement message and before transmitting the communication data. The initiation data and the communication data are preferably transmitted to the second device without using a push-to-talk server.
The method preferably further includes determining an address for establishing communication with the second device either from a user of the first device or from memory of the first device, without communicating with a device external to the first device. The step of transmitting is preferably initiated by pushing a button on the first device. The step of terminating is preferably initiated by releasing a button on the first device. The step of transmitting the initiation data preferably uses a session initiation protocol (SIP) message to transmit the initiation data. The initiation data preferably includes a send-only SIP command. The step of transmitting the initiation data and the communication data preferably uses Real-time Transport Protocol (RTP) or Secure Real-time Transport Protocol (SRTP) to transmit the communication data.
According to a preferred embodiment of the present invention, a communication device includes a transmission device arranged to transmit initiation data to a second communication device to establish a one-way communication session, to transmit communication data to the second communication device, and to terminate the one-way communication session. The initiation data causes the second communication device to receive the communication data and prevents the second communication device from transmitting communication data to the communication device until after the one-way communication session has been terminated.
The transmission device is preferably arranged to wait to receive a first acknowledgement message from the second communication device after transmitting the initiation data. The communication data is preferably transmitted after the communication devices receive the first acknowledgement message. The transmission device is preferably arranged to transmit a second acknowledgement message to the second communication device after receiving the first acknowledgement message and before transmitting the communication data. The transmission device is preferably arranged to transmit the initiation data and the communication data to the second communication device without using a push-to-talk server.
The transmission device is preferably arranged to determine an address for establishing communication with the second communication device either from a user of the communication device or from memory of the communication device, without communicating with a device external to the communication device. The communication device preferably further includes a button arranged to transmit the initiation data to establish the one-way communication session when pushed. The communication device preferably further includes a button arranged to terminate the one-way communication session when released. The transmission device is preferably arranged to use a session initiation protocol (SIP) message to transmit the initiation data. The initiation data preferably includes a send-only SIP command. The transmission device is preferably arranged to use Real-time Transport Protocol (RTP) or Secure Real-time Transport Protocol (SRTP) to transmit the communication data.
Other features, elements, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.
The preferred embodiments of the present invention are discussed below with respect to
Each of the first 1 and second 2 devices can perform one-way communication, which is typically a PTT communication. One-way communication includes establishing a one-way communication session, which is typically a PTT session, between the first 1 and second 2 devices in which communication data is transmitted from the first device 1 to the second device 2 while communication data cannot be transmitted from the second device 2 to the first device 1 or in which communication data is transmitted from the second device 2 to the first device 1 while communication data cannot be transmitted from the first device 1 to the second device 2. Below, one-way communication from the first device 1 to the second device 2 is discussed. However, it should be understood that one-way communication from the second device 2 to the first device 1 is also possible. It should also be understood that communication data includes audio data, video data, or other suitable communication data.
The first 1 and second 2 devices each have a transmission device that preferably includes an antenna 11, 21, an RF processing section A, a baseband processing section B including MAC (Medium Access Control), a CPU C, interface D, memory E, and power supply F. The first 1 and second 2 devices each include a push button 12, 22 connected to the interfaces D.
A user of the first device 1 preferably initiates a one-way communication session by holding down a push button 12 on the first device 1. However, it is possible to use other suitable methods or mechanisms to initiate the one-way communication session. Once the push button 12 is triggered, the first device 1 transmits a message to the second device 2. The message from the first device 1 to the second device 2 can be sent over a network or can be directly sent.
The location or address, e.g. IP address, phone number, and SIP uniform resource identifier (URI), of the second device 2 can be stored in or can be inputted into the first device 1. The one-way communication session is typically only established between two different devices, e.g. the first 1 and second 2 devices, at a time. If a user of the first device 1 desires to communicate with a third device (not shown) different from the second device 2, then the user will need to establish another one-way communication session between the first device 1 and the third device.
The message transmitted from the first device 1 to the second device 2 is preferably an SIP INVITE message that includes special initiation data that indicates that a PPT or a one-way communication session is being requested to be established. The initiation data is preferably included in the header of the SIP INVITE message. For example, the initiation data could be embedded in the “Subject” field or the “display name” part of the uniform resource identifier (URI) in the “To:” or “From:” field of the SIP INVITE message.
An example SIP INVITE message following the standards of RFCC 3261 is provided below in which the initiation data “SyChipPTT” is included in the From: field and the initiation data “SyChipPTT session ZXYKLMN01267” is included in the Subject: field:
It is possible to use only the initiation data “SyChipPTT” included in the From: field, only the initiation data “SyChipPTT session ZXYKLMN01267” included in the Subject: field, or both the initiation data “SyChipPTT” included in the From: field and the initiation data “SyChipPTT session ZXYKLMN01267” included in the Subject: field. The initiation data is not limited to the phrases “SyChipPTT” or “SyChipPTT session ZXYKLMN01267” and can take any readily-recognized form.
Alternatively, the SIP attributes “a=sendonly” can optionally be included in the session description protocol (SDP) body. The SIP INVITE message, as shown by the upper arrow in
After the first device 1 transmits the SIP INVITE message, one or two acknowledgement messages can transmitted between the first 1 and second 2 devices. Typically, the second device 2 transmits a first acknowledgement message to the first device 1, and then, the first device 1 transmits a second acknowledgement message to second device 2. However, it is possible to send only the first acknowledgement message or not to send any acknowledgement messages.
When the second device 2 receives the SIP INVITE message including the initiation data, the second device 2 is informed that a one-way communication session is being transmitted. After receiving the initiation data, the second device 2 mutes its input and acknowledges that a one-way communication session has been established by sending a 200 OK message (first acknowledgement message) to the first device 1. This 200 OK message is shown by the middle arrow in
When the push button is pressed down, the first device 1 performs the steps discussed above and shown in
Accordingly, it is possible to implement a one-way communication system in a preexisting communications network without the need for any network support by relying entirely on the SIP-based control hardware present in the first 1 and second 2 devices. Thus, one-way communication can be performed over networks that have no hardware that provide PTT capabilities.
If the first device 1 receives the 200 OK message, then the first device 1 will send an ACK message to the second device 2 acknowledging that the one-way communication session has been started. After sending this ACK message, the first device 1 will transmit communication data to the second device 2. This transmission of communication data will continue until the user of the first device 1 no longer depresses the push button of the first device 1. Once the user releases the push button, the first device will stop sending data to the second device 2 and will transmit a BYE message to the second device 2. When the second device 2 receives this BYE message, it will terminate the connection between the first device 1 and the second device 2.
It should be understood that the foregoing description is only illustrative of the present invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the present invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications, and variances that fall within the scope of the appended claims.
