KR20080067577A - Apparatus, and associated method, for selecting whether to reject as invalid a data segment received at a communication station - Google Patents

Abstract

An apparatus for selecting whether a received data segment is valid or not, and a method thereof are provided to determine whether the contents of the data segment is valid or not in response to the measurement of a BER(Bit Error Rate) of a header portion of the data segment. An apparatus for selecting whether a received data segment is valid or not includes a payload portion error measurer(38), a header portion error measurer(42), and a data segment acceptor(48). The payload portion error measurer checks a CRC(Cyclic Redundancy Code) in the payload portion of the data segment. If the CRC of the payload portion passes the CRC check, the payload portion error measurer provides a signal which indicates that the payload portion passes the CRC check. The header portion error measurer is coupled to the payload portion, and is configured to analyze a header portion of the data segment in response the signal. The header portion error measurer measures a bit error rate of the header portion. The data segment acceptor accepts selectively the data segment valid in response to the bit error rate of the header portion which is measured by the header portion error measurer and the CRC check passing.

Description

Apparatus and associated method for selecting whether or not to reject a data segment received at a communication station as invalid {APPARATUS, AND ASSOCIATED METHOD, FOR SELECTING WHETHER TO REJECT AS INVALID A DATA SEGMENT RECEIVED AT A COMMUNICATION STATION}

The present invention generally relates to a method for determining whether to reject or accept data of a data segment received at a communication station, such as GPRS / EDGE, an EDGE-enabled mobile station in a cellular communication system. More specifically, the present invention relates to an apparatus and related method for making a determination as to whether to reject or accept the content of a data segment as valid or invalid in response to the measurement of the BER (bit error rate) of the header portion of the data segment. It is about.

If the header portion FEC FEC protected by FEC coding indicates a BER worse than the selected threshold, the data segment is considered invalid and discarded. Conventional schemes that only use data segment payload CRC (cyclic redundancy code) analysis to determine whether to accept a data segment as valid are likely to make CRC checks wrong. Data segment due to incorrect passing of CRC check of the payload portion of the data segment, by measuring the BER of the header portion of the data segment and using this BER measurement to determine whether to reject this data segment as invalid. Is incorrectly accepted as valid.

Digital communication technology is widely used in many different types of communication systems. In general, the use of digital communication technology allows for the communication of data at significantly higher data throughputs with higher efficiency than is permitted through the use of conventional analog communication technology. The information communicated may be converted to digital form or otherwise provided. Typically, data is formatted according to a standardized formatting scheme known to both the transmitting station sending the data and the receiving station terminating the data. The transmitting station and the receiving station are interconnected via a communication channel through which data is communicated. In a wireless communication system, a communication channel is defined, at least in part, over a wireless link extending between communication stations.

In a real communication system, the communication channel is incomplete. That is, data is sometimes distorted while being transmitted on a communication channel. Once the information content of data is received at the receiving station, this information content is distorted. If the distortion is severe, the information content of the data cannot be recovered.

Various schemes have been developed to correct the distortion introduced on the data or provide a way to compensate for this distortion. One type of this approach is to code the data before data communication to increase the redundancy of the data. And, sometimes the communication of a known value or sequence of values is also used to determine whether the data received at the receiving station has been properly decoded.

An exemplary digital cellular communication system, GPRS / EDGE (Data Transfer Enhancement Technology for Universal Packet Radio Service / GSM Evolution) cellular communication system communicates coded data between a transmitting station and a receiving station in accordance with the implementation of the EDGE communication service. . Data formatted into radio blocks is sent by the transmitting station to the receiving station. The radio block includes a header portion and a payload portion. And the payload portion of the radio block includes a 12 bit CRC (cyclic redundancy code) and, optionally, is FEC protected. The header portion of the radio block includes an 8 bit CRC and is also more strongly FEC (forward error correction) protected than the payload portion. The CRC of the payload portion of the radio block is used to determine whether the payload portion has been correctly decoded. However, sometimes there is a possibility that an incorrect determination is made that the payload portion is decoded correctly even when the payload portion is decoded incorrectly. That is, wrong judgment is made. Using a 12-bit CRC, a random data block may incorrectly pass a CRC check once every 4,096 times. In long data transfers, tens of thousands of radio blocks may be received. In poor signal conditions, several corrupted radio blocks pass the CRC check and may be mistakenly accepted as valid.

Once the data is accepted as valid, the data is passed to the upper logical layer to form a PDU (Packet Data Unit) that is part of the data block. The upper layer's data block is typically formed of dozens of lower layer radio blocks. If a bad, ie corrupted radio block forms part of a higher layer data block, then the higher data-higher layer data block is also corrupted. If corruption is detected, global retransmissions are caused for the entire radio block of the upper layer data block, resulting in significant delay and significantly unnecessary retransmissions. In addition, higher layer retries are sometimes based on timeouts. Corruption in the higher layer may further stop the data flow until the timer expires and triggers the retransmission of the data block. A stalled data flow leads to insufficient data throughput.

Therefore, a better and improved way of ensuring that a damaged radio block is not mistakenly accepted as valid is useful.

Significant improvements in the present invention have been made in the light of this background information regarding the communication of data using digital communication techniques.

Accordingly, the present invention advantageously provides an apparatus and associated method for determining whether to accept or reject data of a data segment received at a communication station such as GPRS / EDGE, an EDGE capable mobile station of a cellular communication system as valid data.

Through operation of an embodiment of the present invention, in response to the measurement of the BER (bit error rate) of the header portion of the data segment, a method is provided for making a determination as to whether to accept or reject the content of the data segment as valid.

In a first aspect of the invention, a determination is made as to whether a data segment header portion FEC protected by forward error correction (FEC) coding exhibits a BER worse than a selected threshold, and rejects the data segment (i.e., the data segment is Not accepted as valid data). The data segment includes both a header portion and a payload portion. All of this (eg, the header portion and the payload portion) is FEC protected and the header portion is more strongly FEC protected than the payload portion.

In another aspect of the invention, when a data segment is received, the bit error rate meter measures the bit error rate of the header portion of the data segment. In a typical communication scenario, multiple data segments, radio blocks are received in succession. In such a scenario, the bit error rate meter measures the bit error rate of each data segment received at the communication station. In other implementations, other quality indication measurements are made in the header portion of the data segment.

In another aspect of the invention, once the bit error rate of the header portion of the data segment is measured by a bit error rate meter, it is compared with a threshold. If the bit error rate is worse than the threshold, the data segment is rejected as invalid. In other words, if the BER of the header portion of the data segment is worse than the threshold, it is concluded that the payload portion of the data segment is of poor quality. Accordingly, rejection of data segments is of poor quality. Rejection of a data segment excludes the possibility that the data segment is incorrectly judged to be valid by another mechanism.

In another aspect of the invention, the threshold at which the measured bit error rate is compared is selectable. That is, the threshold is a selected value and is selected from among a plurality of different thresholds. The determination of whether the segment should be rejected as invalid data is made in part depending on the selection of the threshold. In one implementation, the data segment is coded according to a selected one of the plurality of coding schemes. Different coding schemes have different coding parameters. The selection of the threshold is for example in response to the coding scheme used to code the data of the data segment. During the course of a typical scenario where a large number of data segments are communicated in series, if the coding scheme for coding the data segments changes, the thresholds used for comparison purposes may change accordingly.

In another aspect of the invention, prior to the measurement of the bit error rate of the header portion by the bit error meter, a CRC check is first performed when the payload portion of the data segment is first performed. If the CRC check of the payload portion of the data segment passes, the bit error rate meter measures the bit error rate of the header portion of the data segment. The measured bit error rate is then compared against a threshold and a determination is made as to whether to accept this data segment as valid or to reject the data segment. Thereby, in order for the data segment to be accepted as valid, the data segment must pass both the CRC check of the payload portion and the bit error rate measurement test of the header portion. Due to a false pass of the CRC check, even if the data segment is incorrectly accepted as valid, the data segment is not accepted as valid because additional bit error rate measurements and comparisons with thresholds are performed. If the CRC check passes, acceptance of the data segment is only conditionally accepted. In order for a data segment to be accepted as valid, the data segment must further pass a bit error rate measurement test on the header portion. Alternatively, BER measurements are first performed and used to determine whether the BER is better than the threshold. If better than the threshold, a CRC check is performed on the payload portion.

In another aspect of the invention, the radio block is formed of a header portion and a payload portion. Both the header portion and the payload portion are FEC protected and CRC protected. However, the header portion is more strongly FEC protected than the payload portion. Due to the stronger FEC protection of the header part, the BER measurement of the header part becomes reliable, even if the distortion value of the payload part makes the CRC check unreliable, the BER measurement of the header part becomes reliable. And, for example, in addition to the CRC check performed in the payload portion, BER measurement is performed in the header portion of the radio block as an additional check.

In another embodiment of the present invention, if the data segment is accepted as valid, the data is passed to a higher logical layer, and the data (ie, the payload portion) forms part of a data block such as a PDU (packet data unit). Used. By confirming that the bit error rate of the header portion of the lower logical layer data segment is better than the threshold, the upper layer data block containing the data of the passed data segment is less likely to contain corrupted data. As a result, communication performance is improved.

Therefore, in these and other aspects, an apparatus and associated method for selecting whether to receive a received data segment as valid are provided. The data segment has a header portion and a payload portion. The header portion error measurer is configured to analyze the header portion of the data segment. The header portion error meter is configured to measure the bit error rate of the header portion. The data segment acceptor is optionally configured to at least partly accept the data segment as valid in response to the bit error rate of the header portion measured by the header portion error meter.

According to the present invention, with the method and apparatus of the present invention, it is possible to determine whether to reject or accept data of a data segment received at a communication station, such as GPRS / EDGE, an EDGE-enabled mobile station in a cellular communication system.

Therefore, referring first to FIG. 1, a communication system, generally indicated at 10, provides wireless communication to a mobile station represented by mobile station 12.

Communication is performed between the mobile station and the portion of the network represented here as the radio access network (RAN) 14. The communication is carried out via an air interface represented by segment 16 through which network-originated data is delivered to mobile station 12, and the mobile-originated data is wirelessly communicated via this air interface. Delivered to an access network and a communication device coupled thereto. The radio access network is coupled to an external network, here referred to as packet data network (PDN) 18. Communication devices, such as communication device 22, are located within a range of communication connection possibilities with a packet data network. The communication device represents a communication endpoint of communication with the mobile station 12 in accordance with the communication session.

In an exemplary implementation, the wireless portion of the communication system includes GSM / GPRS / EDGE (Mobile Communication Globalization System / Universal Packet Radio Service / Data Transfer Enhancement Technology for GSM Evolution), a cellular communication system that provides high speed data communication services. . More generally, the wireless portion of a communication system represents any of a variety of communication systems that provide data services through communication of data segments. In an example implementation, this data segment is often referred to as an EDGE radio block formed of a header portion and a payload portion, respectively. Thus, the following detailed description describes exemplary operations for an example implementation of a cellular communication system that provides an EDGE communication service, but the techniques of the present invention are also similarly applicable to other types of communication systems. In addition, downlink communication is described. The uplink communication is similar and may be similar to the operation of an entity in the network portion of the system 10, although not shown separately.

The mobile station here includes transceiver circuitry, denoted by receive (RX) portion 26 and transmit (TX) portion 28. Data delivered to the mobile station is received at the receiving portion, and data delivered by the mobile station is transmitted by the transmitting portion. When the mobile station is used in accordance with the implementation of the data communication service, radio block, the data segment is received at the mobile station. Due to fading conditions, noise, receiver front end distortion, and other sources of distortion that distort the value of the data segment, the value of the data segment operating on the mobile station will be different from the corresponding value when it is transmitted. If the mobile station cannot compensate for the distortion through data correction or retransmission, communication problems arise. As mentioned above, when CRC (cyclic redundancy code) analysis is performed, there is a possibility that an invalid radio block is accepted as valid. If a data block that is accepted as valid is passed on to the upper logical layer, the delivery of the incorrectly accepted data block causes problems for the higher layer communication and potentially a significant communication delay if the entire data block formed of numerous radio blocks must be retransmitted. Cause

In accordance with the operation of an embodiment of the present invention, the mobile station 12 further includes the apparatus of the embodiment of the present invention, shown generally at 36. Apparatus 36 is formed of functional entities that may be implemented in any desired manner, such as, for example, algorithms executable by processing circuitry. The functions performed by the entities of the apparatus may be further implemented at any location, such as a controller of the mobile station or a portion of the transceiver circuit of the mobile station.

Here, the apparatus comprises a payload partial error measurer 38, a header partial error measurer 42, a comparator 44, a threshold selector 46 and a data segment acceptor 48.

A data segment 52, ie a radio block, together with the header portion 54 and the payload portion 56 is also shown in FIG. 1. When a data segment is received at the mobile station, the received portion detects the delivery of the data segment at the mobile station. And an indication of the data segment displayed here via line 62 is provided to the payload partial error meter. In an example implementation, the payload portion error meter includes a CRC checker that checks the CRC included in the payload portion of the received data segment. Upon confirming the CRC check, i.e., if the CRC check passes, an indication of the CRC check pass displayed via line 64 is provided to the header portion error meter 42. An indication of the detected data segment provided via line 62 is also provided to the header portion error meter. The error meter operates to measure the bit error rate for the header portion of the radio block provided to the error meter. And an indication of the measurement result is provided via line 72. In an example implementation, the header partial error meter operates only if an indication is provided that the CRC check was successfully passed by the payload partial error meter.

The bit error rate values measured by the header portion error meter 42 are compared in the comparator against a threshold that appears here to be provided via line 76. In an example implementation, the threshold is a selectable value, selected by threshold selector 46. The result of the comparison performed by the comparator is provided to data segment acceptor 48, as indicated here via line 82. The data segment acceptor selects via line 62 whether to accept the data segment provided here as valid. If the data segment is accepted as valid, then the data segment is passed as indicated by line 84 here. If the comparison indicates that the bit error rate of the header portion of the data segment is worse than the selected threshold applied over line 76, the data segment acceptor does not accept the data segment as valid, but instead the data segment occurs on line 66. Rejected with a rejection mark. Here, line 66 extends to the transmitting portion of the mobile station, with the result that the reject indication is returned to the network to request retransmission of the rejected data segment. Since error detection is performed in the lower logical layer, when an entire group of radio blocks formed of data segments is combined into a packet data unit or other data blocks similarly formed into a plurality of data segments, an error is detected only in the upper logical layer. Without a delay that can be associated with, the error is quickly corrected. In another embodiment, the BER measurement and analysis of the header portion is performed before the CRC check performed on the payload portion.

In an example implementation, the operation of the threshold selector for selecting the threshold applied to the comparator 44 via line 76 is performed in response to an input applied to the selector via line 92. Line 92 indicates the coding level of the data segment detected at the receiving portion of the mobile station. The coding scheme in the communication session in which EDGE data is provided is one of nine coding levels designated as MCS-1 through MCS-9. In response to the coding scheme used, the threshold selector selects the threshold used in response to the coding scheme. And, accordingly, the comparison result and the operation of the acceptor 48 also depend in part on the threshold selected by the selector.

2 is a process diagram (generally indicated at 102) illustrating a process of operation for an embodiment of the present invention. The process begins (starting block 104) and detects a data segment, such as an EDGE radio block (block 106).

A CRC check is performed on the payload portion of the detected data segment (block 108). A determination is then made as to whether the payload portion of the data segment has passed the CRC check (decision block 112). If the check does not pass, a negative branch is taken and the data segment is rejected (block 114). Conversely, if the CRC check passes, a positive branch is taken. Passing the CRC check conditionally accepts the data segment. The positive branch extends to block 116 to perform bit error rate measurements of the header portion of the received data segment. Then, as shown in block 118, the measured bit error rate is compared with the selected threshold. A determination is made whether the comparison result indicates whether the bit error rate is better or worse than the selected threshold (decision block 122). If worse than the selected threshold, a reject branch is taken to reject block 114. Otherwise, if an accept branch is taken, the data segment is accepted as valid and passed to the higher logical layer (block 126). When delivered to the upper logical layer, the data segment becomes part of a larger data block, such as a packet data unit.

3 is a method flow diagram (generally indicated at 132) illustrating a method of operation for an embodiment of the present invention. This method facilitates the choice of whether to accept the received data segment as valid. The data segment has a header portion and a payload portion.

First, as shown in block 134, the bit error rate of the header portion of the data segment is measured. Then, as indicated by block 136, a determination is made whether the bit error rate of the header portion is better than the first selected threshold.

Thereafter, as indicated by block 138, the data segment effectively responds, at least in part, to the determination that the bit error rate of the header portion is better than the first selected threshold.

Thereby, a scheme is provided for determining the validity of a received data segment based on the measurement of the bit error rate of the header portion of the data segment. Conventional schemes that tend to erroneously accept a data segment as valid using only the analysis of the CRC included in the payload portion of the data segment are supplemented or improved due to additional or alternative analysis of the bit error rate of the header portion. The problems associated with incorrectly accepting data in a damaged data segment as valid are reduced.

1 is a functional block diagram of a wireless communication system in which an embodiment of the present invention may operate.

2 is a process diagram illustrating a process of operation for an embodiment of the present invention.

3 is a method flow diagram illustrating a method of operation for an embodiment of the present invention.

Claims (16)

An apparatus 36 for selecting whether to accept a received data segment as valid, wherein the data segment 52 has a header portion 54 and a payload portion 56, the apparatus 36 comprising: A payload portion error measurer 38 configured to check for a cyclic redundancy code (CRC) in the payload portion 56 of the data segment 52, if the CRC of the payload portion passes the CRC check; A payload portion error meter 38, providing a signal indicating that the payload portion has passed the CRC check; Interlocked with the payload portion and configured to analyze the header portion 54 of the data segment 52 in response to the signal indicating that the CRC of the payload portion has passed a CRC check, the bits of the header portion A header portion error meter 42 configured to measure an error rate; At least in part, a data segment acceptor 48 configured to selectively accept the data segment as valid in response to the CRC check pass and the bit error rate of the header portion measured by the header portion error meter 42 Apparatus for selecting whether to accept the received data segment, characterized in that 36. The comparator 44 of claim 1 further configured to receive an indication of the bit error rate measured by the header partial error measurer 42 and further configured to compare the indication of the bit error rate with a first selected threshold. Device 36 for selecting whether to accept the received data segment. 3. The data segment acceptor (48) of claim 2, wherein the data segment acceptor (48) is configured to receive an indication of a comparison made by the comparator, and wherein the data segment acceptor (48) receives the data segment in response to the indication of the comparison. The device 36 selecting whether to accept the received data segment, which is accepted as valid. 3. The apparatus (36) of claim 2, wherein said selected threshold comprises a selected one of a first selected value and at least a second selected value. 5. The received data segment of claim 4, wherein the data segment 52 is encoded by a selected coding scheme, and wherein a selected one of the first selected value and at least a second selected value respectively responds to the selected coding scheme. Acceptance selection device 36. 6. The threshold selector of claim 5, configured to receive an indication of the selected encoding scheme and configured to select a selected one of the first selected value and at least a second selected value in response to the indication of the selected coding scheme. Device 36 for selecting whether to accept the received data segment further comprising. 2. The data segment 52 of claim 1 wherein the data segment 52 is received at a mobile station 12 defined with respect to a logical layer, and wherein the header portion error measurer 42 and the data segment acceptor 48 are at a first logical layer. The device 36 selecting whether to accept the received data segment, which is implemented. 8. The mobile station of claim 7, wherein the mobile station 12 further comprises a second logical layer logically located above the first logical layer, wherein the data segment acceptor 48 comprises a payload portion of the data segment 52. And further configured to provide a value of to the second logical layer. The method of claim 8, wherein the payload portion of the data segment that is accepted as valid and provided to the second logical layer forms part of a second logical layer data block once provided to the second logical layer. Device 36 for selecting whether to accept the received data segment. The data segment acceptor (48) of claim 1, wherein the data segment acceptor (48) is configured such that the bit error rate measured by the header partial bit error rate meter (42) is better than a first selected threshold and that the payload partial error meter (38) is used. And if the measured bit error rate is better than a second selected threshold, configured to accept the data segment as valid. The data segment 52 of claim 1, wherein the data segment 52 comprises an EDGE-formatted data segment, wherein the data segment of the EDGE format after acceptance of the data segment acceptor 48 is part of a data block. And 36, configured to accept the received data segment. A method 132 for selecting whether to accept a received data segment as valid, wherein the data segment 52 has a header portion 54 and a payload portion 56, wherein the method includes: Performing 108 a check of a cyclic redundancy code (CRC) in the payload portion, if the CRC of the payload portion passes the CRC check, Measuring a bit error rate of the header portion (134); Determining (136) whether a bit error rate of the header portion is better than a first selected threshold, If the CRC of the payload portion passes the CRC check and the bit error rate of the header portion is better than the first selected threshold, At least in part, accepting the data segment as valid in response to a determination during the determination operation that a bit error rate of the header portion is better than the first selected threshold (138). The method (132) of selecting whether to accept the received data segment, characterized in that it comprises a. 13. The method of claim 12, further comprising selecting the first selected threshold. 14. The method according to claim 13, wherein the data segment is coded according to a selected coding scheme, and wherein the selection of the first selected threshold during the selection step is in response to the selected coding scheme. ). 13. The method of claim 12, further comprising measuring a CRC of the payload portion. 16. The method of claim 15, wherein the operation of the accepting step further responds to a CRC of the payload portion.

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