Method for forming acknowledgement data in a wireless communication system and a wireless communication system

• US 6,760,877 B1
• Filed: 05/11/2000
• Issued: 07/06/2004
• Est. Priority Date: 05/12/1999
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Lappeteläinen, Antti, Smolander, Visa Tapio
• Primary Examiner(s): Tu, Christine T.
• Application Number:
  US09/569,007
• Time in Patent Office: 1,517 Days
• Field of Search: 714/748, 714/751, 714/752, 714/758, 714/746, 714/712, 714/819, 714/820, 714/821, 714/4, 714/37, 714/43
• US Class Current: 714/748
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04L 1/1642 Formats specially adapted for sequence numbers
• CPC Class Codes: H04L 69/324 in the data link layer [OSI layer 2], e.g. HDLC
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04W 76/10 Connection setup

Abstract

The invention relates to a method in a wireless communication system (1) comprising wireless terminals (MT1-MT4), a communication channel (CH) and at, least one access point (AP1, AP2) and access point controller (AC1, AC2). The method comprises the steps of activating at least one data transmission connection between the wireless terminal (MT1-MT4) and the access point (AP1), in which information is transmitted in packets, forming data frames (FR) for the transmission of the packets, supplementing said data frame (FR) with at least one item of error checking data, in whose formation at least a part of the information contained in the data frame (FR) is used, converting said data frames (FR) into signals to be transmitted on the communication channel, receiving signals transmitted on the communication channel and converting them into data frames, forming reference.data corresponding to at least one item of error checking data on the basis of the information received in the data frame (FR), comparing the received error checking data with said reference data, and setting up an acknowledgement message, in which information on the received parts of the data frame (FR) is transmitted from the device (MT1-MT4) receiving the data frames to the device (AP1, AP2).

Claims

1. Method in a wireless communication system comprising at least one wireless terminal, a communication channel and at least one access point and at least one access point controller, the method comprising the steps of:

activating at least one data transmission connection between the at least one wireless terminal and the at least one access point, in which information is transmitted in packets,

forming at least one data frame for the transmission of the packets,

supplementing said at least one data frame with at least one item of error checking data, in whose formation at least a part of the information contained in the at least one data frame is used,

converting said at least one data frame into signals to be transmitted from the at least one access point on the communication channel,

receiving signals transmitted on the communication channel and converting the received signals into at least one data frame in the at least one wireless terminal,

forming reference data corresponding to at least one item of error checking data on the basis of information received in the at least one data frame,

comparing the error checking data with said reference data, and

setting up an acknowledgement message from the at least one wireless terminal receiving the data frames to the at least one access point transmitting the data frames,

wherein the method also comprises the steps of;

determining at least a first reference value,

determining at least a first error type and a second error type,

forming a measuring value on the basis of the received signal,

if the error checking data and the reference data do not match, a comparison is performed for comparing said first reference value with said measuring value, wherein one of the first error type and second error type is selected on the basis of the comparison for incorrectly received parts of the at least one data frames, and

supplementing said acknowledgement message with information on the error type.

2. The method according to claim 1, characterized in that the conversion of data frames into signals to be transmitted on the communication channel comprises modulation stages and encoding stages, wherein the reference value is selected on the basis of the modulation and encoding used in the conversion.

3. The method according to claim 1, characterized in that also a second reference value and a third error type are determined.

4. The method according to claim 3, characterized in that the error type is determined as the first error type, if the measuring value is smaller than said first reference value;

the error type is determined as the third error type, if the measuring value is greater than said second reference value;

in other cases the type is determined as the second error type.

5. The method according to claim 1, characterized in that the measuring value is formed by measuring the signal strength of at least part of the signal received during the data frame.

6. The method according to claim 1, characterized in that the measuring value is formed by measuring the signal power level, preferably the average power level, of at least part of the signal received during the data frame.

7. The method according to claim 1, characterized in that the signals to be transmitted on the communication channel comprise at least one initial synchronization part, wherein the measuring value is formed by measuring the signal power level in the initial synchronization part.

8. The method according to claim 1, characterized in that the method comprises the steps of:

forming at least one data field (D) in the frames,

allocating transmission slots (TS1-TSn) in said data field (D) for the transmission of packets of said data transmission connection,

providing the packets with the packet error checking data on the basis of the information contained in the packet, wherein

packets of said data transmission connection are received, the strength of the received signal is measured for each packet,

on the basis of the information contained in each received packet, reference data is formed which is compared with the error checking information received in the packet in question,

if the packet error checking data and the packet reference data do not match, said first reference value and said second reference value are compared with the strength of the received signal, wherein for the incorrectly received packets, the error type is defined as the first error type, if the strength of the received signal is smaller than said first reference value;

the error type is defined as the third error type, if the strength of the received signal is greater than said second reference value;

in other cases the error type is defined as the second error type, and

status data is defined for the data field in such a way that in the data frame with packets marked as incorrect, the status data is marked as;

the first error type, if the number of the first error type is at least equal to the number of other error types in the incorrectly received packets of the data frame,

the second error type, if the number of the second error type is greater than the number of other error types in the incorrectly received packets of the data frame,

the third error type, if the number of the third error type is greater than the number of other error types in the incorrectly received packets of the data frame,

faultless, if all the packets of the data frame belonging to said data transmission connection are faultlessly received.

9. The method according to claim 8, characterized in that in the method, the data frames are also provided with at least one control field (C), and the error checking data of the control field is formed on the basis of the information contained in the control field (C), wherein in the wireless terminal, on the basis of the information received in the control field (C), control field comparison data is formed which is compared with the error checking data of the control field received in said control field (C), wherein the control field (C) is marked as incorrectly received, if the error checking data of the control field and the reference data of the control field do not match.

10. The method according to claim 9, characterized in that in the method, said error type data is formed on the basis of one or several received data frames, and that said information on the error type comprises at least two parts, wherein

if the second error type is more frequent than the first error type in the status data, one part of the error type data is set to contain information about the second error type, in other cases information about the first error type;

and

if one or several control fields (C) are marked as incorrectly received, the second part of the error type data is set to contain information about the incorrectly received control field (C), in other cases information about the faultlessly received control field (C).

11. The method according to claim 9, characterized in that in the method, a measuring value is also formed on the basis of the signal received in the control field, and said first reference value and said second reference value are compared with said measuring value, wherein on the basis of the comparison, one of said error types is selected for the control field (C) marked as incorrect.

12. The method according to claim 1, characterized in that the first error type is fading of the signal, the second error type is interference, and the third error type is signal compression.

13. The method according to claim 12, characterized in that for the transmission of signals, there are at least two channels available on the communication channel, wherein if the error type is the first error type, the access point will not conduct a channel change, and if the error type is the second or third error type, the access point will conduct a channel change.

14. The method according to claim 1, characterized in that data frames are transmitted from the access point (AP1, AP2) and received in the wireless terminals (MT1-MT4).

15. A wireless communication system comprising

at least one wireless terminal,

a communication channel,

at least one access point, and at least one access point controller,

means for activating at least one data transmission connection between the wireless terminal and the at least one access point,

means for forming at least one data frames for transmission of information in packets,

means for setting up at least one item of error checking data on at least part of information contained in the at least one data frame and for annexing it in said data frame,

means for converting the at least one data frame into signals to be transmitted from the at least one access point on the communication channel,

means for receiving signals transmitted on the communication channel and for converting the received signals into at least one data frame in the at least one wireless terminal,

means for forming reference data corresponding to at least one item of error checking data on the basis of information received in the at least one data frame, and

means for comparing the error checking data with said reference data,

means for transmitting an acknowledgement message from the at least one wireless terminal to the at least one access point that transmitted the data frames,

wherein that the wireless communication system also comprises:

means for determining at least a first reference value,

means for determining at least a first error type and a second error type,

means for forming a measuring value on a basis of the received signal,

means for performing a comparison for comparing at least the first reference value and said measuring value,

means for selecting one of said at least first error type and second error type for incorrectly received parts of the at least one data frame on the basis of the comparison, and

means for supplementing said acknowledgement message with information on the error type.

16. The wireless communication device according to claim 15, characterized in that it also comprises means for determining a second reference value and means for determining a third error type.

17. The wireless communication system according to claim 16, characterized in that the error type to be selected is arranged to be the first error type, if the measuring value is smaller than said first reference value;

the third error type, if the measuring value is greater than said second reference value;

in other cases the second error type.

18. The wireless communication system according to claim 16, characterized in that:

the data frames comprise at least one data field (D), transmission slots (TS1-TSn) are allocated from said data field (D) for the transmission of packets of said data transmission connection,

each packet is provided with packet error checking data on the basis of the information contained in the packet, wherein the communication system comprises;

means for receiving packets of said data transmission connection,

means for forming packet reference data on the basis of the information contained in each received packet,

means for comparing the packet reference data with the error checking information received in the packet in question,

means for measuring the strength of the signal received during each packet,

means for comparing said first reference value with the strength of the received signal, wherein for incorrectly received packets it is arranged that the error type to be defined is the first error type, if the strength of the received signal is smaller than said first reference value;

the third error type, if the strength of the received signal is greater than said second reference value;

in other cases the second error type, and

means for determining the status data for the data field in the data frame, wherein the status data to be marked is arranged to be

the first error type, if the number of the first error type is at least equal to the number of the second error type in the incorrectly received packets of the data frame,

the second error type, if the number of the second error type is greater than the number of the first error type in the incorrectly received packets of the data frame, faultless, if all the packets of the data frame belonging to said data transmission connection are faultlessly received.

19. The wireless communication system according to claim 18, characterized in that the data frames also comprise at least one control field (C) and that the control field is, on the basis of information contained in the control field (C), provided with error checking data for the control field.

20. The wireless communication system according to claim 16, characterized in that the means for converting the data frames into signals to be transmitted on the communication channel are provided in the access point, and the means for receiving signals transmitted on the communication channel and for converting them into data frames are provided in the wireless terminal.

21. The wireless communication system according to claim 16, characterized in that the system comprises at least a first wireless terminal and a second wireless terminal, and that the first wireless terminal comprises at least means for transmitting data frames and the second wireless terminal comprises at least means for receiving data frames.

22. The wireless communication system according to claim 16, characterized in that the system is a wireless local area network.

23. The wireless communication system according to claim 15, characterized in that the means for forming the measuring value comprise means for measuring the signal strength on at least part of the signal received during the data frame.

24. The wireless communication system according to claim 15, characterized in that the means for forming the measuring value comprise means for measuring the signal power level, preferably the average power level, on at least part of the signal received during the data frame.

25. The wireless communication system according to claim 15, characterized in that the means for converting the data frames into signals to be transmitted on the communication channel comprise means for annexing at least one initial synchronization part to the signals, wherein the means for forming the measuring value comprise means for measuring the signal strength in the initial synchronization part.

26. A method in a wireless communication system comprising at least one wireless terminal, a communication channel and at least one access point and at least one access point controller, the method comprising:

activating at least one data transmission connection between the at least one wireless terminal and the at least one access point, in which information is transmitted in packets,

forming at least one data frame for the transmission of the packets,

supplementing the at least one data frame with at least one item of error checking data, in whose formation at least a part of the information contained in the at least one data frame is used,

converting the at least one data frame into signals to be transmitted from the at least one transmitting device on the communication channel,

receiving signals transmitted on the communication channel and converting the received signals into at least one data frame in at least one receiving device,

forming reference data corresponding to at least one item of error checking data on the basis of information received in the at least one data frame,

comparing the received error checking data with the reference data, and

setting up an acknowledgement message from the at least one receiving device receiving the data frames to the at least one transmitting device transmitting the data frames,

wherein the method also comprises;

determining at least a first reference value,

determining at least a first error type and a second error type,

forming a measuring value on the basis of the received signal, and

if the error checking data and the reference data do not match, a comparison is performed for comparing said first reference value with said measuring value, wherein one of said the first error type and second error type is selected on the basis of the comparison for incorrectly received parts of the at least one data frames, and

supplementing said acknowledgement message with information on the error type.

27. The method of claim 26 wherein the at least one transmitting device is the at least one wireless terminal and the at least one receiving device is the at least one access point.

28. The method of claim 26 wherein the at least one transmitting device is the at least one access point and the at least one receiving device is the at least one wireless terminal.

29. A wireless communication system comprising

at least one wireless terminal,

a communication channel,

at least one access point, and

at least one access point controller,

means for activating at least one data transmission connection between the wireless terminal and the at least one access point,

means for forming at least one data frame for transmission of information in packets,

means for setting up at least one item of error checking data on at least part of information contained in the at least one data frame and for annexing it in said at least one data frame,

means for converting the at least one data frame into signals to be transmitted from the at least one transmitting device on the communication channel,

means for receiving signals transmitted on the communication channel and for converting them into at least one data frame in the at least one receiving device,

means for forming reference data corresponding to at least one item of error checking data on the basis of information received in the at least one data frame, and

means for comparing the error checking data with said reference data,

means for transmitting an acknowledgement message from the at least one receiving device to the at least one transmitting device that transmitted the data frames,

wherein the wireless communication system also comprises:

means for determining at least a first reference value,

means for determining at least a first error type and a second error type,

means for forming a measuring value on a basis of the received signal,

means for performing a comparison for comparing said at least the first reference value and said measuring value,

means for selecting one of said at least first error type and second error type for incorrectly received parts of the at least one data frame on the basis of the comparison, and

means for supplementing said acknowledgement message with information on the error type.

30. The wireless communication system of claim 29 wherein the at least one transmitting device is the at least one wireless terminal and the at least one receiving device is the at least one access point.

31. The wireless communication system of claim 29 wherein the at least one transmitting device is the at least one access point and the at least one receiving device is the at least one wireless terminal.