QUASISYNCHRONOUS RESERVATION REQUESTS

• US 20080304507A1
• Filed: 06/06/2008
• Published: 12/11/2008
• Est. Priority Date: 06/11/2007
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Irvine, David, Becker, Donald W.
• Granted Patent: US 7,953,060 B2
• Time in Patent Office: Days
• US Class Current: 370/449
• CPC Class Codes: H04J 13/007 LAS, i.e. LA, LS and LAS codes
• CPC Class Codes: H04W 74/00 Wireless channel access
• CPC Class Codes: H04W 74/002 Transmission of channel access control information

Abstract

Methods and apparatuses are presented for communicating using a shared communication medium. A request is sent in a request signal space where the request represents a code sequence that is a member of a set of code sequences. Each member is characterized by an autocorrelation function that has a peak centered at zero time offset. Each member is further characterized by a cross correlation function. The cross correlation function has a low correlation window having a width and surrounding a zero time offset. An assignment is received that assigns the request to a transmission opportunity in a scheduled transmission signal space. The assignment is made in response to detecting the code sequence from receiving multiple requests having relative timing offsets less than the width of the low correlation window. A data transmission is sent using the assigned transmission opportunity in the scheduled transmission signal space.

Claims

1. A method for communicating using a shared communication medium comprising:

sending a request in a request signal space, the request representing a code sequence that is a member of a set of code sequences, each member characterized by an autocorrelation function having a peak centered at a zero time offset, each member further characterized by a cross correlation function defined with respect to each other member, the cross correlation function having a low correlation window having a width and surrounding a zero time offset;

receiving an assignment for assigning the request to a transmission opportunity in a scheduled transmission signal space, the assignment made in response to detecting the code sequence from receiving multiple requests having relative timing offsets less than the width of the low correlation window; and

sending a data transmission using the assigned transmission opportunity in the scheduled transmission signal space.

2. The method of claim 1 wherein the set of code sequences corresponds to a generalized orthogonal code set, wherein the cross correlation function with respect to each other member of the set of code sequences is zero if the relative timing offsets are less than the width of the low correlation window.

3. The method of claim 1 wherein the set of code sequences corresponds to a generalized quasi-orthogonal code set, wherein the cross correlation function with respect to each other member of the set of code sequences is small if the relative timing offsets are less than the width of the low correlation window.

4. The method of claim 1 wherein the width of the low correlation window is determined by a length of the code sequence and a number of members in the set of code sequences.

5. The method of claim 4 wherein the length of the code sequence and the number of members in the set of code sequences are selected so that the relative timing offsets of the multiple requests are less than the width of the low correlation window.

6. A method for communicating using a shared communication medium involving a plurality of nodes including a first node and a second node, the method comprising:

at the second node, receiving a request from the first node in a request signal space, the request representing a code sequence that is a member of a set of code sequences, each member characterized by an autocorrelation function having a peak centered at a zero time offset, each member further characterized by a cross correlation function defined with respect to each other member, the cross correlation function having a low correlation window having a width and surrounding a zero time offset;

at the second node, sending an assignment for assigning the request to a transmission opportunity in a scheduled transmission signal space, the assignment made in response to detecting the code sequence from receiving multiple requests having relative timing offsets less than the width of the low correlation window; and

at the second node, receiving a data transmission using the assigned transmission opportunity in the scheduled transmission signal space.

7. The method of claim 6 wherein the set of code sequences corresponds to a generalized orthogonal code set, wherein the cross correlation function with respect to each other member of the set of code sequences is zero if the relative timing offsets are less than the width of the low correlation window.

8. The method of claim 6 wherein the set of code sequences corresponds to a generalized quasi-orthogonal code set, wherein the cross correlation function with respect to each other member of the set of code sequences is small if the relative timing offsets are less than the width of the low correlation window.

9. The method of claim 6 wherein the width of the low correlation window is determined by a length of the code sequence and a number of members in the set of code sequences.

10. The method of claim 9 wherein the length of the code sequence and the number of members in the set of code sequences are selected so that the relative timing offsets of the multiple requests are less than the width of the low correlation window.

11. An apparatus for communicating using a shared communication medium comprising:

a first node capable of sending a request in a request signal space, the request representing a code sequence that is a member of a set of code sequences, each member characterized by an autocorrelation function having a peak centered at a zero time offset, each member further characterized by a cross correlation function defined with respect to each other member, the cross correlation function having a low correlation window having a width and surrounding a zero time offset;

wherein the first node is capable of receiving an assignment for assigning the request to a transmission opportunity in a scheduled transmission signal space, the assignment made in response to detecting the code sequence from receiving multiple requests having relative timing offsets less than the width of the low correlation window; and

wherein the first node is capable of sending a data transmission using the assigned transmission opportunity in the scheduled transmission signal space.

12. The apparatus of claim 11 wherein the set of code sequences corresponds to a generalized orthogonal code set, wherein the cross correlation function with respect to each other member of the set of code sequences is zero if the relative timing offsets are less than the width of the low correlation window.

13. The apparatus of claim 11 wherein the set of code sequences corresponds to a generalized quasi-orthogonal code set, wherein the cross correlation function with respect to each other member of the set of code sequences is small if the relative timing offsets are less than the width of the low correlation window.

14. The apparatus of claim 11 wherein the width of the low correlation window is determined by a length of the code sequence and a number of members in the set of code sequences.

15. The apparatus of claim 14 wherein the length of the code sequence and the number of members in the set of code sequences are selected so that the relative timing offsets of the multiple requests are less than the width of the low correlation window.

16. An apparatus for communicating using a shared communication medium comprising:

a second node capable of receiving a request from a first node in a request signal space, the request representing a code sequence that is a member of a set of code sequences, each member characterized by an autocorrelation function having a peak centered at a zero time offset, each member further characterized by a cross correlation function defined with respect to each other member, the cross correlation function having a low correlation window having a width and surrounding a zero time offset;

wherein the second node is capable of sending an assignment for assigning the request to a transmission opportunity in a scheduled transmission signal space, the assignment made in response to detecting the code sequence from receiving multiple requests having relative timing offsets less than the width of the low correlation window; and

wherein the second node is capable of receiving a data transmission from the first node using the assigned transmission opportunity in the scheduled transmission signal space.

17. The apparatus of claim 16 wherein the set of code sequences corresponds to a generalized orthogonal code set, wherein the cross correlation function with respect to each other member of the set of code sequences is zero if the relative timing offsets are less than the width of the low correlation window.

18. The apparatus of claim 16 wherein the set of code sequences corresponds to a generalized quasi-orthogonal code set, wherein the cross correlation function with respect to each other member of the set of code sequences is small if the relative timing offsets are less than the width of the low correlation window.

19. The apparatus of claim 16 wherein the width of the low correlation window is determined by a length of the code sequence and a number of members in the set of code sequences.

20. The apparatus of claim 19 wherein the length of the code sequence and the number of members in the set of code sequences are selected so that the relative timing offsets of the multiple requests are less than the width of the low correlation window.