Method and Apparatus for Robust Transmission of Control Information in a Wireless Communication Network

• US 20100165847A1
• Filed: 05/12/2009
• Published: 07/01/2010
• Est. Priority Date: 12/30/2008
• Status: Active Grant

• Current Assignee: General Electric Company, Telefonaktiebolaget LM Ericsson
• Original Assignee: General Electric Company
• Inventors: Bergljung, Christian, Kamuf, Matthias, Lincoln, Bo
• Granted Patent: US 8,005,039 B2
• Time in Patent Office: Days
• US Class Current: 370/241
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0058 Allocation criteria
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

A base station includes transmitter and associated processing circuits. The transmitter circuits are configured to transmit control information and data traffic to mobile terminals in repeating transmission intervals, each interval having defined control and data portions. The processing circuits are configured to dynamically determine that the control portion has insufficient resources for transmitting control information to one or more of the mobile terminals, and, in response, at least temporarily transmit control information in the data portion, rather than in the control portion, for a selected one or more of the mobile terminals. Correspondingly, a mobile terminal is configured to selectively search for and decode control information in the data portion of one or more transmission intervals, rather than in the control portion.

Claims

1. A method in a wireless communication network base station of transmitting downlink control information to a plurality of mobile terminals, said method comprising:

transmitting control information and data traffic to the mobile terminals in repeating transmission intervals, each transmission interval having a control portion that is defined for transmitting control information to targeted ones of the mobile terminals and a data portion that is defined for transmitting data traffic to targeted ones of the mobile terminals;

dynamically determining that the control portion has insufficient resources for transmitting control information to one or more of the mobile terminals; and

responsive to said determining, at least temporarily transmitting control information in the data portion, rather than in the control portion, for a selected one or more of the mobile terminals.

2. The method of claim 1, further comprising, responsive to said determination, selecting the selected one or more of the mobile terminals according to a function that minimizes transmission resources in the data portion that are given over to the transmission of control information.

3. The method of claim 1, wherein dynamically determining that the control portion has insufficient resources for transmitting control information to one or more of the mobile terminals comprises determining that an overall information-carrying capacity of the control portion is insufficient, in consideration of collective amounts of control information to be sent in the control portion and corresponding coding gains needed for reliable reception of that control information.

4. The method of claim 1, wherein dynamically determining that the control portion has insufficient resources for transmitting control information to one or more of the mobile terminals comprises determining that radio reception conditions at a particular one or more of the mobile terminals are such that a maximum coding gain achievable for control information transmitted in the control portion is insufficient for reliable reception of control information at the particular one or more of the mobile terminals.

5. The method of claim 4, wherein at least temporarily transmitting control information in the data portion, rather than in the control portion, comprises transmitting control information targeted to the particular one or more of the mobile terminals in the data portion using a coding gain that is higher than the maximum coding gain achievable in the control portion.

6. The method of claim 1, wherein dynamically determining that the control portion has insufficient resources for transmitting control information to one or more of the mobile terminals comprises determining that a maximum coding gain achievable for transmission of control information in the control portion is insufficient for reliable reception of control information by a given one of the mobile terminals, and wherein at least temporarily transmitting control information in the data portion comprises, at least for so long as the maximum coding gain of the control portion is deemed insufficient, transmitting control information that is targeted to the given mobile terminal in the data portion, rather than in the control portion.

7. The method of claim 6, further comprising reverting back to transmitting control information that is targeted to the given mobile terminal in the control portion, responsive to determining that the maximum coding gain achievable in the control portion is sufficient for reliable reception of control information by the given mobile terminal.

8. The method of claim 1, wherein transmitting control information and data traffic to mobile terminals in repeating transmission intervals comprises transmitting an Orthogonal Frequency Division Multiplex (OFDM) signal including repeating sub-frames as said repeating transmission intervals, each sub-frame comprising a Physical Downlink Control Channel (PDCCH) as said control portion of the sub-frames, and a Physical Downlink Shared Channel (PDSCH) as said data portion of the sub-frames.

9. The method of claim 8, wherein at least temporarily transmitting control information in the data portion, rather than in the control portion, for a selected one or more of the mobile terminals comprises transmitting control information that is targeted to the selected one or more mobile terminals on the PDSCH, rather than on the PDCCH.

10. The method of claim 9, further comprising at least temporarily defining an Extended PDCCH (E-PDCCH) on the PDSCH, and wherein transmitting control information that is targeted to the selected one or more mobile terminals on the PDSCH comprises transmitting the control information that is targeted to the selected one or more mobile terminals on the E-PDCCH.

11. A base station for use in a wireless communication network, said base station comprising:

transmitter circuits configured to transmit control information and data traffic to mobile terminals in repeating transmission intervals, each transmission interval having a control portion that is defined for transmitting control information to targeted ones of the mobile terminals and a data portion that is defined for transmitting data traffic to targeted ones of the mobile terminals;

one or more processing circuits that are operatively associated with the transmitter circuits and are configured to;

dynamically determine that the control portion has insufficient resources for transmitting control information to one or more of the mobile terminals; and

responsive to said determination, at least temporarily transmit control information in the data portion, rather than in the control portion, for a selected one or more of the mobile terminals.

12. The base station of claim 11, wherein the base station is configured to, responsive to said determination, select the selected one or more of the mobile terminals according to a function that minimizes transmission resources in the data portion that are given over to the transmission of control information.

13. The base station of claim 11, wherein the base station is configured to dynamically determine that the control portion has insufficient resources for transmitting control information to one or more of the mobile terminals by determining that an overall information-carrying capacity of the control portion is insufficient, in consideration of collective amounts of control information to be sent in the control portion and corresponding coding gains needed for reliable reception of that control information.

14. The base station of claim 11, wherein the base station is configured to dynamically determine that the control portion has insufficient resources for transmitting control information to one or more of the mobile terminals by determining that radio reception conditions at a particular one or more of the mobile terminals are such that a maximum coding gain achievable for control information transmitted in the control portion is insufficient for reliable reception of control information at the particular one or more of the mobile terminals.

15. The base station of claim 14, wherein the base station is configured to at least temporarily transmit control information in the data portion, rather than in the control portion, by transmitting control information targeted to the particular one or more of the mobile terminals in the data portion using a coding gain that is higher than the maximum coding gain achievable in the control portion.

16. The base station of claim 11, wherein the base station is configured to dynamically determine that the control portion has insufficient resources for transmitting control information to one or more of the mobile terminals by determining that a maximum coding gain achievable for transmission of control information in the control portion is insufficient for reliable reception of control information by a given one of the mobile terminals, and wherein the base station is configured to at least temporarily transmit control information in the data portion by, at least for so long as the maximum coding gain of the control portion is deemed insufficient, transmitting control information that is targeted to the given mobile terminal in the data portion, rather than in the control portion.

17. The base station of claim 16, wherein the base station is configured to revert back to transmitting control information that is targeted to the given mobile terminal in the control portion, responsive to determining that the maximum coding gain achievable in the control portion is sufficient for reliable reception of control information by the given mobile terminal.

18. The base station of claim 11, wherein the base station is configured to transmit control information and data traffic to mobile terminals in repeating transmission intervals by transmitting an Orthogonal Frequency Division Multiplex (OFDM) signal including repeating sub-frames as said repeating transmission intervals, each sub-frame comprising a Physical Downlink Control Channel (PDCCH) as said control portion of the sub-frames, and a Physical Downlink Shared Channel (PDSCH) as said data portion of the sub-frames.

19. The base station of claim 18, wherein the base station is configured to at least temporarily transmit control information in the data portion, rather than in the control portion, for a selected one or more of the mobile terminals by transmitting control information that is targeted to the selected one or more mobile terminals on the PDSCH, rather than on the PDCCH.

20. The base station of claim 19, wherein the base station is configured to at least temporarily define an Extended PDCCH (E-PDCCH) on the PDSCH, and to transmit control information that is targeted to the selected one or more mobile terminals on the PDSCH by transmitting the control information that is targeted to the selected one or more mobile terminals on the E-PDCCH.