COMMUNICATION SYSTEM USING OFDM FOR ONE DIRECTION AND DSSS FOR ANOTHER DIRECTION

• US 20070223406A1
• Filed: 05/31/2007
• Published: 09/27/2007
• Est. Priority Date: 03/09/2001
• Status: Active Grant

• Current Assignee: Adaptix, Inc. (Acacia Research Corporation)
• Original Assignee: Adaptix, Inc. (Acacia Research Corporation)
• Inventors: Zhang, Wenzhong, Li, Xiaodong, Liu, Hui
• Granted Patent: US 8,040,855 B2
• Time in Patent Office: Days
• US Class Current: 370/278
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 5/143 for modulated signals H04L5/1469 takes precedence
• CPC Class Codes: H04W 16/10 Dynamic resource partitioning
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/10 Open loop power control
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

A method and apparatus for wireless communication are described. In one embodiment, a method for communicating with a subscriber comprises transmitting orthogonal frequency domain multiplexing (OFDM) signals to the subscriber, and receiving direct-sequence spread spectrum (DSSS) signals from the subscriber.

Claims

1. A method for communicating with a subscriber, the method comprising:

transmitting orthogonal frequency domain multiplexing (OFDM) signals to the subscriber, wherein receipt of the OFDM signals by the subscriber results in a direct-sequence spread spectrum (DSSS) signal being generated by the subscriber;

wherein said transmitting comprises;

allocating a first portion of OFDM subcarriers to a first subscriber; and

transmitting OFDM signals to the first subscriber according to the allocation.

2. The method of claim 1 wherein the transmitting further comprises:

allocating a second portion of OFDM subcarriers to a second subscriber; and

transmitting OFDM signals to the second subscriber according to the allocation.

3. The method of claim 1 wherein the allocation is responsive to a quality metric received from the first subscriber.

4. The method of claim 1 wherein the quality metric comprises a SNR.

5. The method of claim 1 wherein the allocation is adaptive.

6. The method of claim 1 wherein the allocation comprises allocating only sub-carriers determined to have at least a minimum quality metric.

7. A method for communicating with a subscriber, the method comprising:

transmitting orthogonal frequency domain multiplexing (OFDM) signals to the subscriber, wherein receipt of the OFDM signals by the subscriber results in a direct-sequence spread spectrum (DSSS) signal being generated by the subscriber;

wherein transmitting comprises;

transmitting the OFDM signals in a first frequency range; and

where generating DSSS signals comprises;

generating DSSS signals in a second frequency range.

8. The method of claim 7, wherein the first frequency range and the second frequency range do not overlap.

9. A method for communicating with a plurality of subscribers, the method comprising:

transmitting orthogonal frequency domain multiplexing (OFDM) signals to the plurality of subscribers, wherein receipt of the OFDM signals by the subscribers results in a direct-sequence spread spectrum (DSSS) signal being generated by the subscribers.

10. The communication method of claim 9 wherein the transmitting comprises:

allocating a portion of OFDM subcarriers to at least a subset of said plurality of subscribers; and

simultaneously transmitting OFDM signals to the at least a subset of said plurality of subscribers according to the subcarrier allocation.

11. The method of claim 9, where transmitting OFDM signals comprises transmitting the OFDM signals in a first frequency range and where generating DSSS signals comprises generating DSSS signals in a second frequency range.

12. The method of claim 11, wherein the first frequency range and the second frequency range do not overlap.

13. A communication method, the method comprising:

simultaneously receiving, at one or more subscribers, orthogonal frequency division multiplexing (OFDM) signals, where at least one subcarrier is allocated to one or more subscribers;

transmitting, from one or more subscribers, direct-sequence spread spectrum (DSSS) signals in response to the receiving.

14. A communication method, the method comprising:

receiving orthogonal frequency division multiplexing (OFDM) signals;

demultiplexing multiple sub-carriers of the received OFDM signals;

identifying fewer than all of the demultiplexed sub-carriers that are associated with a subscriber;

outputting user data associated with the identified sub-carriers; and

transmitting direct-sequence spread spectrum (DSSS) signals to a base station in response to the received OFDM signals.

15. A communication method, the method comprising:

transmitting orthogonal frequency division multiple access (OFDMA) signals to at least one subscriber; and

receiving at a base station direct-sequence spread spectrum (DSSS) signals from the at least one subscriber;

wherein the base station and the at least one subscriber comprise a link segment of a bi-directional communication link.

16. The method of claim 15 wherein said bi-directional communication link is asymmetrical.

17. A communication method, the method comprising:

receiving orthogonal frequency division multiple access (OFDMA) signals at a subscriber station; and

transmitting, from the subscriber station, direct-sequence spread spectrum (DSSS) signals to a base station;

wherein the base station and the subscriber comprise a link segment of a bi-directional communication link.

18. The method of claim 17 wherein said bi-directional communication link is asymmetrical.