Method for transfering information between mobile station and honeycomb system

Method for transmitting message between mobile station and cellular system using multiple layer two frames

FIELD OF THE INVENTION The present invention relates to a method for transmitting messages between a plurality of mobile stations and a central switching system, and more particularly, to a method for using more efficient communication procedures through the air interface of a cellular telephone system (air interface) The method of transmitting these messages.

BACKGROUND OF THE INVENTION In a typical land line system, the remote station and the control center are connected by copper or optical fiber lines. Generally speaking, these lines are superior to the cellular telephone system in terms of data throughput and performance integrity. interface. As a result, the frequent management savings required to manage any selected communication link procedures for the landline system becomes a secondary issue.

In the cellular telephone system, in order for the mobile station to communicate with the Cellular Switching System (CSS), an air interface communication link procedure is required. These communication link procedures are used to make and receive cellular telephone calls. The electromagnetic spectrum available for cellular phones is limited and is divided into frequency bands called channels. Each channel is used as a communication link on a shared or dedicated basis. When each channel is used as a communication link on a shared basis, each mobile station can listen to or contend for the same channel. In the case of channel contention, each shared channel can be used by multiple mobile stations that strive to dedicate the channel within a limited time. On the other hand, when each channel is used as a communication link on a dedicated basis, a single mobile station (as long as it needs) is arranged to dedicated the channel.

Since a channel is shared in a cellular phone environment, the data flow capacity and performance integrity of a single message will generally be reduced, so choosing an efficient air interface protocol as the basis of the communication link becomes paramount. Up.

In the communications industry, communication link procedures are usually called layer 2 procedures, and its function includes defining or formulating higher-level information. The traditional layer 2 protocol formulation agencies for bit stuffing and marking characters are now publicly used in land line networks to formulate higher-level messages, which are called layer 3 messages. These layer 3 messages can be sent between each peer entity in the mobile station and the cellular switching system. The air interface protocol has become of paramount importance as the basis of the communication link.

In the communications industry, communication link procedures are usually called layer 2 procedures, and its function includes defining or formulating higher-level information. The traditional layer 2 protocol formulation agencies for bit stuffing and marking characters are now publicly used in land line networks to formulate higher-level messages, which are called layer 3 messages. These layer 3 messages can be sent between each peer entity in the mobile station and the cellular switching system.

The communication between the mobile station and the cellular switching system will be described with reference to Figures 1 and 2. Figure 1 shows a plurality of layer 3 messages 11, layer 2 frames 13, and channel bursts 15. The channel burst 15 is the shortest or smallest transmission event that occurs between the mobile station and the CSS. In Figure 1, although the channel bursts are separated by time, they are not necessarily separated. In other words, when a channel burst has just ended, the next channel burst can begin. A channel pulse 15 includes a complete layer 2 frame and other correction information, such as errors. Each layer 2 frame is divided into a number of different information groups. One of the information groups is a data information group, which has a finite length and contains at least a part of the layer 3 message 11. Since the length of layer 3 information varies according to the amount of information contained in the layer 3 information, multiple layer 2 frames may be required to transmit a single layer 3 message. As a result, because there is a one-to-one correspondence between channel bursts and layer 2 frames, multiple channel bursts may be required to transmit a complete layer 3 message. When multiple channel bursts are required to transmit a layer 3 message, the multiple bursts are usually not continuous bursts. Since it takes time to receive, process, and respond to the received pulse, the pulses used to transmit the layer 3 message are sent in the form of staggered arrangement as shown in FIG. 2. In Figure 2, path A represents a communication between a mobile station A and CSS. In this example, mobile station A uses every sixth uplink (mobile station to CSS direction) channel burst to transmit a layer 3 message to CSS. As a result, while mobile station A uses different related uplink bursts to transmit layer 3 messages, other mobile stations, such as mobile station B, can also send layer 3 messages to the CSS.

In the time division multiple access (TDMA) based on the cellular telephone system, the inherent channel coding format has been proposed as a means to achieve the basic layer 2 frame limitation function, and it is the traditional way to eliminate the above-mentioned bit stuffing and marking characters. Effective method of layer 2 framing mechanism. These TDMA channels can be used for dedicated or shared base output. These TDMA channels are basically a transmission unit or burst sequence, where each burst has a fixed information carrying capacity. As a result, each burst usually only carries a portion of the layer 3 message. When the TDMA channel is used on a shared basis, it can be considered as a digital control channel, where multiple mobile stations either strive for their own use when sending layer 3 information to the cellular switching system (in the uplink), or jointly Listen to the CSS in an attempt to receive the possible layer 3 messages they want (on the downlink). In the uplink direction, multiple mobile stations try to communicate with the cellular switching system on the basis of competition, while multiple mobile stations listen to layer 3 messages sent by the cellular switching system in the downlink direction. However, the improvement of the additional layer 2 flow characteristics is still desirable, because both the uplink, namely, the random connection channel (RACH) and the downlink, namely, the connection response channel (ARCH), may have multiple differences at any given moment. The layer 3 message is waiting to be processed.

In known systems, any given layer 3 message must be carried using as many TDMA channel bursts as needed to transmit the entire layer 3 message. The last TDMA channel burst used to send different layer 3 messages may not fully utilize its capacity, because the last part of the layer 3 message may not occupy all the data segments. In these systems, no measures are taken to make any pending Layer 3 messages sent in the remaining capacity of the data segment. As a result, whenever another independent and different layer 3 message is in a transmittable state, and at the same time, the last sent layer 3 message can be completed in any given TDMA channel burst, the existing The system wastes a lot of available TDMA channel burst capacity.

Summary of the Invention Therefore, there is a need for a transmission method to transmit messages between a mobile station and a cellular switching system in a manner that improves the capacity of the information burst. Therefore, the object of the present invention is to provide a transmission method between the mobile station and the cellular switching system. A method for transferring messages between systems in which a given channel burst contains information belonging to separate and different layer 3 messages.

Therefore, one aspect of the present invention is to provide a method for transmitting messages between a mobile station and a cellular switching system, which uses the concept of a layer 2 protocol frame carried in a channel burst, wherein the The frame is first divided into multiple information groups. Then a frame type information group identifies the type of the frame. The end of the first layer 3 message and the start of the second layer 3 message are identified at the end of an information group, which is used to define the various parts of the layer 3 message contained in a continuous data information group. Finally, the layer 2 frames are transmitted through uplink channel or downlink channel bursts.

Hereinafter, the present invention will be described in more detail with reference to the preferred embodiments of the present invention. These embodiments are only examples and are shown in the accompanying drawings.

Figure 1 shows multiple layer 3 messages, layer 2 frames and channel bursts in a communication system; Figure 2 shows the communication path between the mobile station and the cellular switching system in the form of channel bursts; Figure 3 shows The start frame in an embodiment of the present invention; Figure 4 shows an intermediate frame in an embodiment of the present invention; Figure 5 shows an end frame in an embodiment of the present invention; Figure 6 shows an implementation of the present invention The dedicated layer 2 frames in the example; FIG. 7 shows the shared layer 2 frames in an embodiment of the present invention.

Detailed description of the present invention Although the following description is within the scope of a time division multiple access cellular switching system, those skilled in the art will understand that the present invention can be applied to other digital communication applications, such as code division multiple access. (CDMA).

In this embodiment, the layer 2 protocol of the present invention is composed of four different types of layer 2 frames, namely, a start frame, an intermediate frame, an end frame, and an extended frame. These different types of layer 2 frames are suitable for transmitting layer 3 information in a cellular telephone system. For ease of description, the following description assumes a TDMA channel burst structure of the Fast Associated Control Channel (FACCH) as described in EIA/TIA IS-54B, but the present invention is not limited to this. The fast associated control channel is a signaling channel used to transmit control and management information between the cellular switching system and the mobile station. In this embodiment, the structure of the fast-associated control channel is such that there are 65 information-carrying or load-bearing bits available for use in each TDMA channel burst.

In a cellular system, there can be multiple mobile stations ready to communicate with the cellular switching system at the same time. However, only one mobile station per uplink can communicate with the CSS. As a result, those mobile stations that are ready to transmit compete for the available uplink channel burst (contention process), and only one mobile station will be allowed to connect to (win a contention process) the available uplink channel burst String sequence. If a mobile station is forced to transmit on a competitive basis, each layer 3 message has a waiting time when trying to connect to the CSS, resulting in increased throughput delay and system throughput performance will be degraded. However, the present invention provides a means to avoid multiple competitions by indicating the logical association or connection of separate and different layer 3 information from one mobile station. In the present invention, once a mobile station has won a competition process, that is, it is allowed to connect with the CSS, it can use this connection mechanism to send all separate and different layer 3 messages that are ready for transmission. This makes the system have better throughput performance, that is, reduces the amount of connection with CSS on the basis of competition. The present invention also uses fewer channel bursts to carry multiple layer 3 messages, that is, any given channel burst can contain information from two different layer 3 messages.

Each layer 2 frame is divided into multiple information groups. These information groups are an additional burst indication information group, a data information group, a message end information group, a frame type information group, a frame type change information group, and an initial information group. /Repeated information group, and a reverse information group. Hereinafter, each information group will be described with reference to the drawings.

Fig. 3 shows the start frame in an embodiment of the present invention. The frame 10 is divided into four information groups: frame type information group 12; initial/repetition information group 14; data information group 16; and CRC (cyclic redundancy check) information group 18. Since a layer 3 message may be longer than a single layer 2 frame, multiple layer 2 frames may be required to transmit a layer 3 message. As a result, the frame type information group 12 identifies the frame type as a start frame, an intermediate frame, and an end frame, or an extended frame. In this embodiment, the frame type information group 12 occupies 2 bits of the channel burst payload. The frame type information group 12 is the first information group of the start frame 10. In this way, the first 2 bits of each channel burst identify the frame type, where 00 indicates the start frame, 01 indicates the intermediate frame, 10 indicates the end frame, and 11 means extended frame. The start frame type is used for the initial pulse of multi-burst layer 3 messaging.

Next to the start frame 10 is the initial/repeated information group 14 of 1 bit. Transmission bursts are sometimes received incorrectly. As a result, a transmission burst may need to be retransmitted. In order for the CSS to operate normally, it is necessary to identify whether the received burst is an initial transmission burst or a repetitive transmission burst. The initial/repetitive information group 14 indicates whether a channel burst is transmitted for the first time or repeatedly. For example, "0" in the initial/repetition information group 14 indicates that the channel burst is sent for the first time, and "1" in the initial/repetition information group 14 indicates that the channel burst is sent again.

The data block 16 constitutes the main part of the start frame 10. The data information group 16 contains a part of the layer 3 information to be transmitted. Finally, the start frame includes a cyclic redundancy check (CRC) block 18 used to detect errors. The cellular switching system uses this cyclic redundancy check block 18 to determine whether any uplink channel bursts have been received in error. The method of using the CRC information group to determine the error detection is well-known in the art, so it will not be described.

FIG. 4 shows an intermediate frame 20 in an embodiment of the present invention, and the intermediate frame is used for an intermediate channel burst of multi-burst layer 3 message transmission. The intermediate frame 20 includes a frame type information group 12, an initial/repetition information group 14, a data information group 16 and a CRC information group 18, which have been described above in conjunction with FIG. 3. The intermediate frame is appended with a reversal information group 22 to provide the required header alignment to maintain a clear and consistent line from the intermediate frame to the end frame whenever the information in the remaining layer 3 message is longer than 45 bits Transition point. The inversion information group is added to the intermediate frame to avoid undesirable transmission conditions that will occur when the remaining 46-bit layer 3 message is to be transmitted. If there is no inverted information group, all the remaining 46 bits of data will be sent in an intermediate frame, and the end frame after that will contain an empty data information group. This difficult situation is avoided by adding an inverted information group to the intermediate frame, so that 45 of the remaining 46 bits are transmitted in an intermediate frame, and the last 1 bit is transmitted in the end frame.

Fig. 5 shows the end frame 30 of an embodiment of the present invention. The end frame 30 is used to transmit the last burst of the multi-burst layer 3 message. The end frame 30 includes a frame type information group 12, an initial/repeated group information group 14, a data information group 16 and a CRC information group 18, which have been described with reference to FIG. 3. However, the end frame also includes an additional burst indicator information group 24 to provide a clear indication of message connection, because the additional pulse indicator points to an additional piece of information belonging to a separate and different layer 3 that shares the same uplink process. Whether the pulse is waiting to be processed. When used in a downlink channel, the additional burst indicator information group 24 also provides a clear indication of message connection. If the additional burst indicator field 24 indicates that there is an additional uplink channel burst pending, the cellular switching system will continue to work as if the original layer 3 message is still being transmitted. This ensures that the remaining connection layer 3 messages share the initial uplink connection process, so that they do not have to undergo additional competition.

The fourth frame type, the extended frame, is shown in Figures 6 and 7. In Fig. 6, a dedicated layer 2 frame 40 according to an embodiment of the present invention is shown. This dedicated layer 2 frame is used when layer 3 messages can be transmitted collectively in a single channel burst. That is to say, in this embodiment, the entire layer 3 message can be carried within the 46 bits provided for the data information group. The dedicated layer 2 frame includes a frame type information group 12, a data information group 16 and a CRC information group 18, which have been described above with reference to FIG. 3. However, the layer 2 frame also includes the frame type change information group 26, where "0" represents a dedicated layer 2 frame, and "1" represents a shared layer 2 frame.

Figure 7 shows a shared 2 frame, which is used whenever the first layer 3 message ends and there is additional space available in the data information group, and another separate and different layer 3 message is ready to be transmitted. The common layer is 2 frames 50. When shared layer 2 frames are used in the uplink direction, the sharing of channel bursts basically provides an implicit indication of the layer 3 message connection. However, when shared layer 2 frames are used in the downlink direction, the sharing of channel bursts does not provide an implicit indication of layer 3 information connection. That is, in the uplink direction, the two messages 32 and 34 shown in Figure 7 must come from the same mobile station; while in the downlink direction, the two messages sent from the cellular switching system can be supplied to two different mobile stations. . As a result, when a layer 3 message ends in the middle of the data block, the applicable channel burst capacity will not be wasted. The shared layer 2 frame 50 contains a frame type information group 16, an initial/repetition information group 14, a data information group 16 and a CRC information group 18. These information groups have been described above in conjunction with FIG. 3, and there is another combination in the above figure. 6 The frame type change information group 26 described above. As shown in FIG. 7, in order to provide limited information of the layer 3 message, a message end information group 28 is added to the common layer 2 frame. That is, the message end information group 28 indicates where the first layer 3 message 32 ends and the second layer 3 message 34 starts in the data information group. As a result, the receiving end (CSS or one or more mobile stations) can distinguish these two layer 3 information.

Since multiple mobile stations can fight for the same connection opportunity on a channel, there must be a method to distinguish each mobile station. In an embodiment of the present invention, since the first TDMA channel burst that partially or completely carries layer 3 messages is transmitted from a mobile station to the cellular switching system on a contention basis, it contains the unique characteristics of the transmitting mobile station. information. Containing this unique information called partial echo enables the cellular switching system to provide partial echo feedback to competing mobile stations after correctly receiving the first channel burst, so as to clearly show which mobile stations first channel burst has been Was received correctly.

Although a particular embodiment of the present invention has been described and illustrated, it should be understood that the present invention is not limited to this, as various modifications can be made by those skilled in the art. This application claims that any modifications are included in the spirit and scope of the disclosed and claimed invention.