Method and apparatus for reliable and efficient data communications

Reliable and efficient data communication method and device

The present invention relates to communication with packet data, and more particularly to methods and apparatus for communicating reliable and efficient packet data.

Data packet communication is typical^IIBest effort^l'Packet delivery system. The best effort will be to make the best effort to deliver the packet, that is, it will not discard the packet for no reason. However, in practice, the data packet service is typically a so-called unreliable service because the delivery behavior does not guarantee the delivery result, that is, the packets may be lost, duplicated, or out of order.

However, many data communication applications need or at least benefit from a higher degree of reliability. One way to increase transmission reliability is for two communication units to exchange response messages with each other so that both parties can know when the data transfer is successful. An agreement with retransmission techniques that uses positive acknowledgments and I or negative replies to increase reliability, typically referred to as automatic demand retransmission (ARQ). The transmitter transmits the data unit to the receiver. If the data unit is received by the receiver without error, the receiver sends back a positive response to the transmitter in response. If the data unit is not correctly received by the receiver, that is, if the data unit received is incorrect (at least there are many errors that cannot be effectively corrected) or simply the data unit is not received, then the receiving unit The device transmits a negative response. In the case of a negative acknowledgment, then the receiver transmits a request to the transmitter requesting that the transmitter retransmit the data units that were not received correctly.

A packet can contain some form of polling or status query field. If the transmitter transmits a polling request to the receiver by setting one or more of the polling fields, the receiver transmits the receiver status according to the polling request it receives. Information is sent to the transmitter, for example, to send a response that the packet has been received correctly and without error.

As disclosed above, data packet services are typically unreliable, and packets may be severely delayed or even lost. If this happens, the packet delay or packet loss event must be detected for the transmitter after a long period of time. Once this event is detected, the transmitter must transmit the packet that has been late for a long time. All conditions can result in significant delays in delivery, ultimately resulting in a reduction in effective data throughput.

It is an object of the present invention to provide more reliable but still efficient packet data communication to overcome these problems.

It is another object of the present invention to provide this improved reliability without adding additional complexity or excessively performing the transfer of data packets.

Use one or more data bits and, if possible, use one or more data fields in the data packet that do not contain information, only a small amount of information, or outdated information to enhance the reliability of the data communication.

The present invention improves the reliability of data communication by analyzing a plurality of data units of a group or a block other than one. For example, when a transmitter wishes or needs to transmit a polling request to a receiver, it can transmit a group of more than one data unit. The polling fields for all data units in the group are set to indicate the polling requirements. If at least one of the polling fields of the group of data units received by the receiver indicates a polling request, the receiver sends the status required by the transmitter after receiving the group data unit. Information to the transmitter. But even if there are multiple data units in the data unit, the polling field indicates the polling request.^IThe receiver also transmits only the required status information.

Different from the method of not using the polling field of other data units in the group, which causes bandwidth waste, the present invention uses those other polling fields to improve the reliability of the transmission. This increase in reliability reduces the transmitter-to-receiver transmission delay. In addition, if a data unit is processed individually, an explicit polling field (or other additional field) can be used to detect or correct errors that cannot be detected or corrected.

Preferred embodiments of the present invention are disclosed in a Wideband Coded Multiple Access (WCDMA) radio communication system. In this example, the present invention is implemented in an automatic request retransmission technique implemented in the Radio Link Control (RLC) protocol layer. The present invention is particularly effective in this environment because the packet is transmitted by radio channel. The information, the data is highly susceptible to fading, dispersion, and noise, so the reliability provided by the present invention is particularly useful.

The invention is typically applied to the PDU field rather than the polling field. The transmitter puts the information into the unused PDUs field of one of the group PDUs it transmits. The possibility that the receiver receives at least one specific information in a PDUS is very high. Since this information occupies one or more unused DICS fields, this redundancy and increased reliability do not increase the burden of transmission.

In the following description, for purposes of clarity and clarity, specific details, such as particular embodiments, data flow, signal implementation, protocols, techniques, etc., are described in order to understand the invention. However, it should be apparent to those skilled in the art that the present invention may be practiced otherwise without the specific details. For example, although the disclosure of the present invention implements a particular layer of the data packet stack, i.e., the link layer, those skilled in the art will appreciate that the present invention can be implemented in other protocol layers as well. In other words, descriptions of well-known methods, interfaces, devices, and signal techniques are omitted herein to avoid obscuring the description of the present invention.

The flowchart of Figure 1 formats one of the methods of practicing the invention: initially, the transmitter transmits a group or groups of two or more data units. Each data unit can contain available or^I'data^IlCapital^lNews,^lIcontrol^'IThe data bit field of either the newsletter or both types. After a plurality of these data units are transmitted to the communication channel, the receiver collects the data units in groups (block 10). One or more fields for each of the data units in the received group are then analyzed (block l2). Based on the results of the analysis, it is determined whether the information contained in the field of one of the data units in the group indicates that the operation should be performed (block 14). If not, processing continues. Otherwise, the information in this field can be used to confirm other information in the fields of one or more other data units in the group (block l6). This validation behavior includes simple matching techniques, error detection techniques, and/or error correction techniques that use one or more of the other data units in the group. However, the confirmation, error detection or error correction of the information in the field is an optional function. If the information in the field of only one data unit in the group indicates that an operation should be performed, the operation indicated by the operation may be Execute in a non-confirmed manner. On the other hand, even if there is more than one data unit that contains information in the field indicating that the same operation should be performed, the operation is only performed once for the group (block 18).

The communication system 20 shown in FIG. 2 includes a first communication unit 22 and a second communication unit 24. The data unit is transferred from the first communication unit 22 to the second communication unit 24 via an appropriate communication medium/channel. An example of a non-conforming data unit is a protocol data unit (PDU): however, smaller, larger, or other different formats of information are also possible. Two or more data units of a group from the first communication unit 1 may contain the same field. In the following non-limiting examples, this field is a polling request that requires the receiving communication unit 24 to answer whether each of the transmitted DICS has been successfully received. If the communication unit 24 detects that one or more data units have not received or received an error, then it sends a negative response to the communication unit 22, requesting that one or more of the ones or more are detected. There is a data unit that receives the problem. Although it is not necessary, if only one of the data unit groups transmitted by the communication unit 22 contains a polling request, the receiving communication unit 24 is preferably capable of performing the polling response. Similarly, although it is not necessary, if there are two or more data units in the data unit group that contain polling requirements, unit 24 preferably also only performs one polling response.

The benefits of applying the present invention to the polling field are now illustrated by the Global System for Mobile Communications (UMTS) shown in Figure 3. A representative, connection-oriented external core network shown in the cloud diagram 52 can be, for example, the Public Switched Telephone Network (PSTN) and l or the Integrated Services Digital Network (ISDN). A representative, non-connected, external core network shown in the cloud diagram 54 can be, for example, the Internet. Both core networks are connected to respective service nodes 56. The PSTNIISDN connection-oriented network 52 is coupled to a connection-oriented service node, shown as a mobile switching center (MSC) node 58, which provides circuit switched services. In the existing GSM model, the mobile switching center 58 is connected to the base station controller (BSC) 62 through the interface A: the base station controller (BSC) is through the interface A.^IIt is connected to the radio base station 63. The Internet non-connected navigation network 54 is coupled to an integrated packetized radio service (GPRS) node 60 that provides a packet switched service.

The core network service segment is occupied by 58 and 60 through UMTS terrestrial radio^'The UTRAN interface (IU) is connected to the UTRAN 64. The UTRAN 64 includes one or more radio network controllers 26. Each RNC 66 is connected to a plurality of base stations (BSs) 68 and is connected to any other RNCs in the UTRAN 64. The radio communication between the base station 68 and the mobile radio station (MS) 70 is done by means of a radio interface. The radio access is done according to Wideband CDMA (WCDMA), and each of the assigned radio channels uses a WCDMA spreading code. WCDMA offers broadband and other high-frequency requirements for multimedia services, as well as rugged features such as hand-overs and RARE receivers to ensure high quality.

The radio interface shown in Figure 3 is divided into several protocol layers, and Figure 4 illustrates several lower level layers. In detail, mobile station 70 uses these protocol layers to communicate with peer-to-peer protocol layers in UTRAN 64. Both protocol stacks include: physical layer, data link layer, and network layer. The data link layer is split into two sub-layers: the Radio Link Control (RLC) layer and the Medium Access Control (MAC) layer. In this example, the network layer is divided into a Control Plane Protocol (RRC) and a Surface Protocol (IP).

The physical layer provides information transfer services through the air interface, and uses broadband CDMA to perform the following functions: codec for feedforward error correction, macro-distribution I combination, soft handoff execution, error detection, transmission channel multiplex and Multiplex solutions, mapping transmission channels to physical channels, modulation and expansion of physical channels, demodulation and de-spreading, synchronization of frequency and time, power control, RF processing, and other functions.

The Medium Access Control (MAC) layer provides unacknowledged transfers of Service Data Units (SDUs) between MAC entities of the same class. The MAC function includes: selecting the transmission format of the channel for each transmission channel according to the rate of the data: setting the priority of processing between the data traffic of one user and the data traffic of other users: scheduling the control message Time history, higher layer PDU_SMultitasking and multiplexing and other functions. The RLC performs various functions, including construction, release, and maintenance of RLC connections, variable length segmentation and reassembly, and higher layer PDISSs enter smaller RLCPDUs, concatenated, and error correction by retransmission (ARQ). , in order to deliver higher-level PDUs, repeat detection, flow control and other functions.

The control plane portion of the network layer in the UTRAN constitutes the Radio Resource Control Protocol (RRC). The RRC agreement is responsible for the control of signal transmission to the radio interface, such as radio access azimuth control signaling, measurement reporting, and handoff signaling. The user plane portion of the network layer contains functions performed by the traditional protocol layer 3, such as the well-known Internet Protocol (IP).

The Radio Link Control (RLC) protocol layer contains an Automatic Resend (ARQ) mechanism. The RLC transmitter receives user data and fragments and converts them into RLCPDUs_S. Figure 5A shows an example of an RLC PDU. The first PDU field^I'UIC^IlIt is equivalent to the user 1 controlling the data, and can indicate whether the transmitted message is the data PD U or the control PD U. The^"P^"The field is equivalent to the polling field. When the transmitter wants the receiver to report whether the PDU is correctly received, the bit contained in the polling field is set to^'lI^Il. The^IISerial number^lIThe field indicates the serial number of the data PDU, and the serial number of each new data PDU is added one by one. This data field contains a section of higher-level information. Optional^LlLength indicator^IlAnd extended fields^LlE^I'Included.

The polling bit P in the response PDU is set to^'l1^lIThe receiver can send a status report containing a selective response (SACR) PDU, and the format of the PDU can be as shown in FIG. 5B. The SACR PDU indicates which data PDUS has been received correctly. It is possible to give several data PDU responses and negative responses in the SACR. Just like the above, this^"UIC^"The field indicates whether the transmitted message is a data PDU or a control PDU. The^I'LRSN^IlThe field is equivalent to the most recently received serial number, which indicates the serial number of the most recently received data PDU. Selective^IIE^’’The field is equivalent to an extended field. The^IlStart number^Ll(SSN) indicates the sequence number of the last PDU before the missing PDU. The^lIDot matrix^IIThe length of the field is variable, which shows the data PDUs that were lost or lost between the first received sequence number and the starting sequence number. If the SACRPDU response data PDUs does not include the SSN and bitmap fields, the sequence number will be less than or equal to the LRSN.

The functional block diagram of Figure 6 is one embodiment of the present invention implemented in the RLC layer of a UMTS entity (such as mobile station 70 or RNC 66 shown in Figure 3). In the implementation of this RLC layer, all operations and functions are supervised and controlled by the RLC controller 80. Although Figure 6 shows specific functional blocks, these functions can be performed with any suitable hardware and I or software.

In the RLC layer of the transmitting end of the communication entity, first, the higher level packets are received into the segmentation, concatenation and join RLC header block 82. The higher level packets are segmented and I or concatenated into fixed length PDUs. The length of the PDU is determined by the specific radio access network service established by the specific mobile station communication. Once the RLC header is added to each PDU, they are stored in retransmission buffer 86 and transmit buffer 90 via selector 88. The PDUs stored in the transmit buffer 90 are then sent to the lower MAC layer according to the flow control signal sent by the RLC controller 80 to prepare for transmission, and then transmitted to the physical layer through the physical layer. receiver. Upon receiving a request to resend one or more PDUs (e.g., ACR, NACR or SACR), the RLC controller 80 controls the selector 88 to select the PDUs stored in the retransmission buffer 86 to transmit buffers. The device 90 transmits it out. If a response needs to be obtained from the receiver, the polling bit (P) can be set in block 92.

In this WCDMA example, it is included between the UTRAN 64 and the mobile station 70.^LlLogical connection^IlThe information can be transferred using the radio interface of the physical radio channel, which is split into specific time segments to configure the traffic for the connection or the connection. The number of PDUSs may be transmitted during a particular time period, and may be more than one: and this number may also be changed during the lifetime of the connection. Depending on the transmission rate selected for the connection, the number of unrequested PDICS can be transmitted during one physical channel time zone. At a faster rate, more PDUs are transmitted, and at a slower rate, fewer PDUs are transmitted during that time period. In any event, since PDUs are preferably formatted to have a relatively short length, for example, PDUs with longer lengths have a greater chance of collision, so during a single transmission time interval, a large number of groups are usually transmitted. PDUs.

In the RLC layer of the receiving end of the communication entity, the PDUs transferred during the connection time segment are passed from the physical layer 1 up to the media access channel (WAC) sublayer of the layer 2. From the channel at the level 2 MAC sublayer, a group of PDUs received in the transmission time zone is placed in the receive buffer 96 and then sent to the PDU detection and analysis block 94 for processing. . Block 94 correctly feeds the received PDUs to block 84 where the RLC headers of the PDUs are removed and reassembled into higher level packets, which are then passed to higher Agreement layer.

The PDU side and analysis block 94 determines whether any of the PDUS groups received in the most recent receive time period are polled for any of the PDUs. If the polling bit of one or more PDUs in the PDUs group is set, then block 94 transmits an ACR, NACR or SACR message to the transmitting device via the RLC controller 80 based on the status of the group of PDUs it received. Device. If the detection side and the analysis block 94 detect that there is a PDU loss or reception error, it generates a retransmission request signal, and the format of the signal may be, for example, (I) negative response (ACR/NACR), (2) ) Selective Response (SACR) message as shown in Figure 5B or (3) some other message format. This retransmission request is fed forward to the transmit buffer 90. Through the control of the signal sent by the RLC controller 80, the retransmission request will have a higher transmission priority than the other PDES that is waiting to be transmitted.

Of course, the invention is not limited to application in polling fields or specific communication protocol layers. In fact, the invention can be applied to other data unit fields as well as I or other communication protocol layers. example As shown in Figure 7, the data unit field is a more common format. The data unit field contains one or more flags or other indicator bits and the presence of information bits. If the transmitter decides to transmit information in a field in a data unit of a group of data units, then the transmitter will use similar but unused data unit fields in other data units in the group. To transmit the same presence information to increase the chance that the receiver will correctly receive the presence information. If the data unit field contains redundant presence information, the transmitter will set the flag bit of the data unit field.

After receiving and collecting the data units transmitted by the group, the receiver detects one or more data units of the flag in the group, and decodes the redundant presence information. Perform the operation indicated by the redundant presence information. However, a receiving data unit group, the receiver performs only the operation indicated by the redundant presence information. Since even if there is a data unit in the group that does not correctly receive the information, the other data unit in the group that contains the same presence information may be correctly received, so the reliability will be enhance. Of course, if the receiver has correctly received the presence information, it can ignore the redundant presence information transmitted by other data units in the group.

Although the present invention has been described in terms of specific embodiments, it is understood that the invention is not limited to the specific embodiments described herein. Different formats, implementations, and adaptations may be used to implement the invention in addition to those illustrated and illustrated: modifications, variations, and equivalent configurations are also possible. It should be understood that the disclosure herein is for illustrative purposes only.

The above and other objects, features and advantages of the present invention will be apparent from the description of the appended claims appended claims These drawings are not necessarily emphasized to emphasize the principles of the invention.

Figure 1 is a flow chart of a program for implementing the present invention:

Figure 2 is a block diagram showing an example of a communication system to which the present invention is applied:

The functional block diagram of Figure 3 illustrates a wideband code division multiple access (WCDMA) radio communication system that would be beneficial to the present invention:

Figure 4 illustrates several lower communication protocol layers that can be used in the system shown in Figure 3:

5A and 5B are protocol data units (PDUs) that can be used in the WCDMA radio communication system of FIG. 3:

Figure 6 is a functional block diagram illustrating the invention. How to implement it in the system shown in Figure 3:

Figure 7 is another embodiment of the present invention using a general purpose PDU.