Method for physical layer automatic repeat request for a base station

• US 7,672,265 B2
• Filed: 02/27/2002
• Issued: 03/02/2010
• Est. Priority Date: 08/24/2001
• Status: Expired due to Fees

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Kwak, Joseph A.
• Primary Examiner(s): Cho; Hong
• Assistant Examiner(s): Tsegaye; Saba
• Application Number:
  US10/084,043
• Publication Number:
  US 20030039227A1
• Time in Patent Office: 2,925 Days
• Field of Search: 370/208, 370310-3102, 370/314, 370/320, 370328-330, 370/335, 370/342, 370/349, 370/412, 370/416, 370/428, 370/426, 370/465, 455/68, 455/69
• US Class Current: 370/320
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0034 where the transmitter decides based on inferences, e.g. use of implicit signalling
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1822 involving configuration of automatic repeat request [ARQ] with parallel processes
• CPC Class Codes: H04L 1/1845 Combining techniques, e.g. code combining
• CPC Class Codes: H04L 2001/0096 Channel splitting in point-to-point links
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A physical automatic repeat request method implemented by a base station having a transmitter and a receiver. A physical layer, at the transmitter receives data and formats the received data into packets having a particular encoding/data modulation. The physical layer transmit the packets and retransmits packets upon failure to receive a corresponding acknowledgment for a given packet. An adaptive modulation and coding controller in the transmitter collects retransmission statistics and adjusts the particular encoding/data modulations using the collected statistics.

Claims

1. A method for adjusting data modulation at a base station comprising:

receiving data in data blocks from a higher layer ARQ mechanism at a physical layer transmitter for transmission;

formatting the received data blocks into packets for transmission, the packets being smaller in size than the data blocks, and each packet having a forward error correction (FEC) encoding/data modulation;

appending an error check sequence for each packet;

providing a physical layer ARQ mechanism performing steps including;

transmitting the packets using an orthogonal frequency division multiple access (OFDMA) air interface;

storing the packets for retransmission in a buffer memory incorporated into the physical layer transmitter;

monitoring a return channel for receipt of an acknowledgment for each packet that the packet has been received;

limiting the number of retransmissions to an operator-defined integer value;

clearing the buffer memory after the integer value is reached;

retransmitting an original or selectively modified packet at the physical layer transmitter in response to a failure to receive a corresponding acknowledgement for a given packet;

wherein the physical layer ARQ mechanism and physical layer transmitter operate transparently with respect to the higher layer ARQ mechanism;

receiving and demodulating received packets at a physical layer receiver;

receiving a corresponding acknowledgement for a given packet at the physical layer receiver, wherein a mechanism configured to receive the corresponding acknowledgement for the given packet operates transparently with respect to the higher layer ARQ mechanism;

collecting retransmission statistics and adjusting the FEC encoding/data modulation using the collected statistics at an adaptive modulation and coding controller;

wherein on a condition that the collected retransmission statistics indicate a low number of retransmissions, a higher capacity FEC encoding/data modulation scheme is selected and on a condition that the collected retransmission statistics indicate a high number of retransmissions, a lower capacity FEC encoding/data modulation scheme is selected;

buffering, decoding, and detecting packet errors at a combiner/decoder;

generating an acknowledgement for each received packet in an acknowledgement generator in response to that packet having an acceptable error rate; and

selectively nulling subchannels from an OFDM frequency set for the retransmitting, wherein the use of a poor quality subchannel is precluded for a predetermined period and adding a previously nulled subchannel back into the OFDM frequency set where a retransmission rate or link quality indicates a high quality for the previously nulled subchannel.

2. The method of claim 1 wherein the packets are transmitted using a single carrier having a frequency domain equalization (SC-FDE) air interface.

3. The method of claim 1 wherein a return channel is the fast feedback channel when the packets are transmitted using a code division multiple access (CDMA) air interface.

4. The method of claim 1 further comprising:

identifying a packet as having an unacceptable error rate responsive to receipt of a negative acknowledgment.

5. The method of claim 1 wherein the physical layer ARQ mechanism reduces retransmissions required by the higher layer ARQ mechanism.