HK1101471A - Method for distinguishing different types of data content in data packets in a wireless communication system - Google Patents

Abstract

Apparatus and method for reducing latency in push-to-talk communications in a wireless communication network. Time sensitive push-to-talk (PTT) related messages are identified in a specially designated header, so they can be handled differently by radio mobile devices. These messages with the special designated header are transmitted through signaling channels from a radio transmission unit to a mobile device, as opposed to being transmitted as dedicated channel traffic.

Description

Method for distinguishing different types of data content in data packets in a wireless communication system

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims U.S. provisional patent application serial No. 60/581,790, filed on day 6, month 21, 2004; and U.S. provisional patent application serial No. 60/686,131, filed on 31/5/2005. The contents of these documents are incorporated herein by reference.

Technical Field

The present invention relates to data transfer in a wireless telecommunications system, and more particularly, to identification of the type of data transferred within data packets of a wireless telecommunications system.

Background

In wireless telecommunication systems, push-to-talk (PTT) capabilities are becoming more popular with serving sectors. PTT can support "dispatch" voice services that operate under standard commercial wireless infrastructures, such as Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and global system for mobile communications (GSM). In the dispatch mode, communication between endpoints (end user devices) occurs in a virtual group, where the voice of one "talker" is broadcast to one or more "listeners". A single instance of this type of communication is commonly referred to as a dispatch call, or PTT call for short. A PTT call is an instantiation of a group that defines the characteristics of the call. The group is essentially defined by a member list or associated information such as group name or group identification. Without a wireless multicast channel, each group is formed by a combination of separate point-to-point connections between each endpoint and the application server managing the call. Each endpoint is also referred to as a client.

Fig. 1 illustrates a prior art architecture 100 that supports PTT communications. The architecture includes deploying a single application server area in conjunction with the carrier's CDMA infrastructure and packet data network. Each region in the application server is deployed on a specific portion of the carrier packet data network. Application servers within the area may route traffic between one or more Packet Data Serving Nodes (PDSNs) in the carrier network. A communication device 102 that supports a PTT feature communicates with a base station 104. The base station 104 communicates with the high speed network 106 and sends PTT communications received from the communication device 102 through the base station 104 and the network 106 to a Packet Data Serving Node (PDSN). The PDSN communicates with a high speed network 106 and a network 108 of application servers connected to a PTT network 110. The PDSN forwards the PTT communication to an application server 112 in the PTT network 110.

The application server 112 receives a PTT communication from one member and forwards it to all members of the PTT group. PTT communications are typically received as data packets from the network 110, and PTT communications sent out by the application server 112 are also in the format of data packets. The receiving Mobile Switching Center (MSC) and the connected Base Station (BS) then establish a dedicated channel to transmit the PTT communication to the receiving mobile client (a PTT member).

Fig. 2 illustrates a prior art message flow 200 for PTT call setup. When a PTT user (originator) is ready to make a PTT communication, he presses the PTT activation button on his mobile device 102 and thus generates a PTT request. And the mobile device sends a call request message to the application server 112 (which is also referred to as a PTT scheduler) in response to the PTT request received by the mobile device 102. The application server 112 receives and processes the call request message. The call request processing includes identifying the PTT user, identifying the PTT group to which the PTT user belongs, identifying the members of this PTT group, and preparing an announce call message to be sent to each member of the PTT group.

After the application server 112 sends the announce call messages, each announce call message is received by the MSC and forwarded by the MSC to the BS. The BS broadcasts the announce call message. If the mobile client is active as the target receiver, the mobile client sends an accept call message back to the application server 112. After receiving the accept call message from at least one mobile client, the application server 112 sends a floor grant message back to the originating mobile client. There may be more than one target user in the initiator's PT communication group and the application server 112 grants the floor to the initiator if there is at least one target mobile client active. After receiving the floor grant message, the PTT requesting mobile client (originator) can then engage in a PTT communication. The PTT related messages described above are transmitted as data packets, preferably as Internet Protocol (IP) data packets. Other data formats may also be used to convey these PTT related messages.

The PTT communication set up process described above is time sensitive and network traffic can affect the initial PTT latency shown in fig. 2. The long latency directly affects the users of PTT communications. Accordingly, there is a need for a system and method for reducing PTT latency, and it is to such a system and method that the present invention is primarily directed.

Disclosure of Invention

The apparatus and method of the present invention enable a fast response to PTT related inputs from a PTT communication user. In one embodiment, a method is provided for reducing latency in push-to-talk (PTT) communications between a plurality of mobile devices, wherein each mobile device communicates with a wireless communication network through a signaling channel and a data channel. The method comprises the following steps: receiving a data packet containing a PTT message from a data communication network at a radio signal transmission point, wherein the data packet has a header; checking a header of the data packet; and transmitting the PTT message to the mobile device over a signaling channel instead of waiting to bridge a dedicated access channel when the header of the data packet has a predetermined value.

In another embodiment, an apparatus for reducing latency in push-to-talk (PTT) communications between a plurality of mobile devices is provided, where each mobile device communicates with a wireless communication network through a signaling channel and a data channel. The apparatus includes: a network interface unit for receiving data packets from a data network, each data packet having a header and containing a PTT related message; a storage unit for storing a data packet, wherein the data packet has a header; a controller unit for analyzing a header of the stored data packet; and a radio interface unit for transmitting the stored data packet to the mobile device via a radio signal, wherein the stored data packet is transmitted to the mobile device through a signaling channel if a header of the stored data packet has a predetermined value.

The present apparatus and method are advantageous because they reduce latency in PTT communications between a plurality of users by using constantly established signaling channels rather than periodically established dedicated communication channels. Other advantages and features of the present invention will become apparent after review of the hereinafter set forth brief description of the drawings, detailed description of the invention, and the claims.

Drawings

Fig. 1 is a prior art architecture of a wireless communication network.

Fig. 2 is a prior art message flow for establishing a PTT call.

Fig. 3 is an exemplary embodiment of a header of a data packet.

Fig. 4 is an exemplary embodiment of a service field type in a header of a data packet.

Fig. 5 is a flow chart of an exemplary embodiment of a base station process.

Detailed Description

In this description, the terms "communication device," "wireless communication device," "PTT communication device," "handheld device," "mobile device," and "handset" are used interchangeably. The term "application" as used herein is intended to encompass executable and non-executable software files, raw data, aggregated data, patches (patches), and other code segments. The term "exemplary" means that the disclosed elements or embodiments are only examples, and do not represent any preference of a user. Moreover, in the several figures, like numerals represent like elements, and the articles "a" and "the" include plural references unless otherwise specified in the description.

In general, the systems and methods of the present invention reduce latency delays for push-to-talk (PTT) communications between a wireless device and a wireless communication network. Generally, when a wireless device is ready to transmit a PTT communication to a Base Station (BS), the wireless device sends a channel request to the BS over a signaling channel. The BS will establish a reverse access channel and the wireless device will then transmit a PTT communication to the BS over the reverse access channel. Similarly, when the BS is ready to transmit a PTT communication to a wireless device, the BS broadcasts a paging message over a signaling channel. After the wireless device acknowledges the paging message, the BS establishes a forward access channel to the wireless device and transmits the PTT communication to the wireless device over the forward access channel. The channel request and other PTT call set up messages shown in fig. 2, as well as the PTT communication, are transmitted as data packets through the wireless communication network and the data communication network.

However, PTT communications are not the only services provided to the wireless device user, other services such as email, internet web browser, Short Message Service (SMS), etc. may also be used by the user. The application server 112 handles not only PTT communications between members of the PTT group, but also other services provided to the wireless devices. Data related to all of these services is also transmitted as data packets between the application server 112 and the wireless device 102. These data packets are also processed by the application server 112 and the base station 104 as any other data packets. The additional data packets increase traffic and slow down the wireless communication network.

Because data packets in a wireless communication network support different types of services, they contain data for the different types of services and can be identified by the header of the data packet. According to one embodiment of the present invention, the data packets can be roughly classified into three categories according to their contents: PTT call set-up related messages, PTT communication messages, and other service related messages. PTT call set-up related messages are most time sensitive because they are easily perceived by PTT users. PTT communication messages are also time sensitive because delays can cause jitter in the PTT communication. Other general service-related messages include voice communications, email messages, web browsing messages, and short message services. These non-PTT related messages are less time sensitive. The above-described services are merely examples of services, and those skilled in the art will appreciate that services not listed above may also be classified according to timeliness.

Fig. 3 illustrates a packet header 300 according to one embodiment of the invention. There are a plurality of fields, each marked for a specific function. An 8-bit field, type of service (TOS)302, indicates the type of service of the data in data field 304. FIG. 4 is an illustration 400 of one embodiment of an 8-bit TOS field, wherein the 8-bit TOS field 302 is divided into two subfields: a category selector 402 and a service selector 404. The category selector 402 may be used to identify the category to which the data 304 belongs. For example, the data may be a PTT set up message and thus belong to a time sensitive category; alternatively, the data may be part of the PTT communication and thus belong to a category that is somewhat less time sensitive than the PTT set up message. Service selector 404 may be used to identify the service to which data 304 belongs. The data may be, for example, a PTT call accept message. It should be understood that one skilled in the art may design or use different fields in the data packet header to represent the same information.

The data packet may be generated by the wireless device when the wireless device communicates with the application server 112. The wireless device generates a data packet for the particular service it is processing and sets the TOS field to reflect that service. The wireless device may check the TOS field and decide whether to request a dedicated channel to send the data packet to the base station 104. Alternatively, the wireless device may already know the type of data it is processing and then use that information to decide whether to send the data file to the base station 104 over a signaling channel. After the base station 104 receives the information, it forwards the data packet to the application server 112 for processing.

The application server 112 may also generate data packets and set the TOS field of the message according to the type of service to which the data relates. For example, the application server 112 may receive a call accept message in a data packet from the wireless device and then generate a floor grant message to be sent to the PTT originating user. The floor grant message will be sent in a data packet to the base station 104 serving the PTT originating user. The base station 104 receives the data packet and checks its TOS field. The base station 104 knows that it is a time-sensitive message and transmits a floor grant message over the signaling channel to the wireless device of the PTT originating user. If the data packet contains website related data that does not have a time sensitive message, the base station 104 requests that a dedicated channel be established between itself and the wireless device. The website related data will then be sent over the dedicated channel.

Fig. 5 is a flow chart 500 of a process for processing an incoming data packet at a base station 104. When the base station 104 receives a data packet (step 502), it checks the header of the data packet (step 504). If the TOS field in the packet header is marked as time sensitive, the base station 104 transmits the information of the data packet over the signaling channel (step 506). If the TOS field in the packet header is not marked as time sensitive, the base station 104 will establish a dedicated channel, step 508, and send the data packet to the targeted wireless device via the dedicated channel, step 510.

The following is a use scenario illustrating the present invention. When a first user accesses email through his wireless device, the user may send a reply email to a second user. The wireless device packages the reply mail in a data packet and marks the TOS field of the data packet as not having a time sensitive email service. The wireless device then requests a reverse channel and sends the data packet to the base station 104 over this reverse channel. The base station 104 receives the data packet and forwards the data packet to its destination, the application server 112, according to the header of the data packet.

The application server 112 receives the data packet and learns that it is a reply email to the second user. The application server 112 then forwards the data packet to the base station 104 serving the second user. The base station 104 receives the packet, checks its TOS field, and requests a dedicated access channel. After establishing the forward access channel, the base station 104 sends the data packet to the wireless device of the second user over the forward access channel.

After the second user reads the reply email, he decides to communicate with the first user through the push-to-talk feature. The second user activates the PTT button on his wireless device and the wireless device generates a data packet with a call request message to the application server 112. Because the wireless device considers the data packet to contain a time sensitive message, the wireless device transmits the data packet with the call request message to the base station 104 over a signaling channel. The base station 104 receives the data packet and forwards it to the application server 112.

The application server 112 examines the data packet and knows that it contains a call request message. The application server 112 then checks whether the PTT communication group to which the first and second users belong is in use. If another user has the floor of the PTT communication group, the call request will be denied. If the floor of the PTT communication group is available, the application server 112 identifies the members of the PTT communication group, generates a data packet with a call announce message, and broadcasts the data packet to all members of the PTT communication group.

A data packet with a call announce message is received by the base station 104 serving the first user and the base station 104 checks the TOS field of the data packet header. The base station 104 knows that the data packet contains a time sensitive message and sends the data packet to the first user's wireless device over the signaling channel. If the wireless device is available, it sends back a call accept message as illustrated in FIG. 2. The other steps of fig. 2 are performed in a similar manner and data packets supporting these steps are transmitted via a signaling channel or a dedicated channel depending on the message type identified by the TOS field.

Transmitting a time-sensitive message over a signaling channel, rather than requesting and waiting for a dedicated access channel to be established, can reduce latency in PTT communications and thus make the user more willing to use the PTT feature.

In view of the method being executable on a wireless device provider's computer device or wireless communication device, the method can be performed by a program resident in a computer readable medium, where the program directs a server or other computer device having a computer platform to perform the steps of the method. The computer readable medium may be the memory of a server or may be in a connected database. Further, the computer readable medium can be in a secondary storage media that is loadable onto a wireless communications device computer platform, such as a magnetic disk or tape, optical disk, hard disk, flash memory, or other storage media as is known in the art.

In the case of fig. 5, the method may be implemented, for example, by operating portion(s) of a wireless network, such as a wireless communications device or a server, to execute a sequence of machine-readable instructions. Although the steps are described sequentially, the methods may be performed in a different order or as event-driven processes. The instructions may reside in various types of signal-bearing or data storage primary, secondary, or tertiary media. The media may comprise, for example, RAM (not shown) accessible by, or residing within, the components of the wireless network. Whether contained in RAM, a diskette, or other secondary storage media, the instructions may be stored on a variety of machine-readable data storage media, such as DASD storage (e.g., a conventional "hard drive" or a RAID array), magnetic tape, electronic read-only memory (e.g., ROM, EPROM, or EEPROM), flash memory cards, an optical storage device (e.g., CD-ROM, WORM, DVD, digital optical tape), paper "punch" cards, or other suitable data storage media including digital and analog transmission media.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims. For example, the above description is based on audio PTT communications, it being understood that the apparatus, systems, and methods may be readily modified to support other types of media, such as video, data, and so on. Furthermore, although elements of the invention may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.

Claims (20)

1. A method for reducing latency in a push-to-talk (PTT) communication between a plurality of mobile devices, each mobile device communicating with a wireless communication network through at least one signaling channel and a data channel, the method comprising the steps of:

receiving a data packet containing a PTT message from a data communication network at a radio signal transmission point, the data packet having a header;

checking the header of the data packet; and

the PTT message is transmitted over a signaling channel to a mobile device if the header of the data packet has a predetermined value.

2. The method of claim 1, further comprising the steps of: requesting establishment of a dedicated access channel between the radio signal transmission point and the mobile station if the header in the data packet does not have the predetermined value; and transmitting the PTT message to the mobile device over the dedicated access channel.

3. The method of claim 1, wherein the predetermined value indicates that the PTT message is a time sensitive PTT message.

4. The method of claim 1 wherein the step of inspecting the header of the data packet further comprises the step of inspecting a predetermined field in the header.

5. The method of claim 1, further comprising the step of embedding the PTT message in a signaling message.

6. An apparatus for reducing latency in a push-to-talk (PTT) communication between a plurality of mobile devices, each mobile device communicating with a wireless communication network through signaling channels and data channels, the apparatus comprising:

a network interface unit for receiving data packets from a data network, each data packet having a header and containing a PTT related message;

a storage unit for storing a data packet, the data packet having a header;

a controller unit for analyzing the header of the stored data packet; and

a radio interface unit for transmitting the stored data packets to a mobile device via radio signals,

wherein the stored data packet is transmitted to the mobile device over a signaling channel if the header of the stored data packet has a predetermined value.

7. The apparatus of claim 6, wherein the stored data packet is transmitted to the mobile device over a dedicated access channel if the header of the stored data packet does not have the predetermined value.

8. The apparatus of claim 6, wherein the predetermined value indicates that the PTT related message is a time sensitive PTT message.

9. The apparatus of claim 6, wherein the controller is further capable of checking a predetermined field in the header.

10. The apparatus of claim 6, wherein the radio interface unit embeds the PTT message in a signaling message.

11. An apparatus for reducing latency in a push-to-talk (PTT) communication between a plurality of mobile devices, each mobile device communicating with a wireless communication network through signaling channels and data channels, the apparatus comprising:

receiving means for receiving data packets from a data network, each data packet having a header and containing a PTT related message;

storing means for storing a data packet, the data packet having a header;

analyzing means for analyzing the header of the stored data packet; and

transmitting means for transmitting the stored data packets to a mobile device via radio signals,

wherein the stored data packet is transmitted to the mobile device over a signaling channel if the header of the stored data packet has a predetermined value.

12. The apparatus of claim 11, wherein the stored data packet is transmitted to the mobile device over a dedicated access channel if the header of the stored data packet does not have the predetermined value.

13. The apparatus of claim 11, wherein the predetermined value indicates that the PTT related message is a time sensitive PTT message.

14. The apparatus of claim 11, wherein the means for analyzing the header is further capable of inspecting a predetermined field in the header.

15. The apparatus of claim 11, wherein the means for transmitting the stored data packet is further capable of embedding the PTT message in a signaling message.

16. A computer program on a computer readable medium for reducing latency in a push-to-talk (PTT) communication between a plurality of mobile devices, each mobile device communicating with a wireless communication network through signaling channels and data channels, the computer program comprising computer instructions that when executed by a communication server perform the steps of:

receiving a data packet containing a PTT message from a data communication network at a radio signal transmission point, the data packet having a header;

checking the header of the data packet; and

the PTT message is transmitted over a signaling channel to a mobile device if the header of the data packet has a predetermined value.

17. The computer program of claim 16, further performing the steps of: requesting establishment of a dedicated access channel between the radio signal transmission point and the mobile station if the header in the data packet does not have the predetermined value; and transmitting the PTT message to the mobile device over the dedicated access channel.

18. The computer program of claim 16, wherein the predetermined value indicates that the PTT message is a time sensitive PTT message.

19. The computer program of claim 16, wherein the step of inspecting the header of the data packet further comprises the step of inspecting a predetermined field in the header.

20. The computer program of claim 16, further performing the step of embedding the PTT message in a signaling message.