Method for providing error correction using selective automatic repeat requests in a packet-switched communication system

• US 5,487,068 A
• Filed: 07/29/1994
• Issued: 01/23/1996
• Est. Priority Date: 07/29/1994
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Smolinske, Jeffrey C., Scheibel, Robert C. Jr., Clanton, Christopher L., Tran, Phieu M.
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): Ton, Dang
• Application Number:
  US08/283,085
• Time in Patent Office: 543 Days
• Field of Search: 370/95.1, 370/85.1, 370/95.2, 370/85.2, 370/95.3, 370/85.3, 370/94.1, 370/85.7, 370/118, 370/85.8, 370/104.1, 370/93, 370/94.2, 370/82, 455/58.2, 455/33.1, 455/33.2, 455/33.3, 371/35, 371/32, 375/111, 375/362, 379/59, 379/60
• US Class Current: 370/450
• CPC Class Codes: H04L 1/1685 the supervisory signal being transmitted in response to a specific request, e.g. to a polling signal
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols

Abstract

The method reduces transmission delay by using a selective-repeat automatic repeat request, ARQ, error detection scheme in a packet-switched data communication system. The invention provides a method for a subscriber unit to transmit acknowledgment information using a contention-free channel access scheme in addition to providing for a base site control unit to interrupt a packet currently being transmitted in order to retransmit segments of the packet when the segments have errors.

Claims

1. A method for providing a contention-free access uplink channel for a subscriber unit for transmission of predetermined types of messages in a slotted communication system, comprising the steps of:

A) transmitting, by a base site, a plurality of downlink packets to a first subscriber unit, wherein a packet includes segments;

B) utilizing, by the base site, subscriber unit control information to reserve a next time slot for automatic repeat request information from the first subscriber unit;

C) transmitting, by the first subscriber unit, using the reserved time slot, information on the success/failure of received segments of a first packet of the plurality of packets;

D) temporarily interrupting, by the base site, a packet currently being transmitted to retransmit segments of the first packet that have an error/errors; and

E) recycling to step B until the entire first packet is successfully transmitted.

2. The method of claim 1 wherein the step of transmitting, by the first subscriber unit, using the reserved time slot, information on the success/failure of received segments of a first packet of the actuality of packet further includes halting transmission by another subscriber unit to allow transmission by the first subscriber unit.

3. A method for utilizing downlink channel processing at a base site for providing a contention-free access uplink channel for a first subscriber unit of a plurality of subscriber units for transmission of predetermined types of messages in a slotted communication system, comprising the steps of:

A) receiving, by a base site, a time slot of data from a base site control unit wherein the time slot of data includes at least a first acknowledgment bit;

B) determining whether the at least first acknowledgment bit indicates that the channel is reserved for transmission by the first subscriber unit;

C) where the at least first acknowledgment bit indicates that the channel is unreserved for transmission by the first subscriber unit, determining whether bit(s) for a mode is/are set to information mode;

D) where the mode is set to information mode, setting an acknowledgment field to acknowledgment, broadcasting, by the base site, the slot of data including the acknowledgment field to the plurality of subscriber units, and stopping processing;

E) where the mode is set to an acknowledgment mode, incrementing a modulo count and determining whether the modulo count is equal to zero;

F) where the modulo count is unequal to zero, setting the acknowledgment field to acknowledgment, broadcasting, by the base site, the slot of data including the acknowledgment field to the plurality of subscriber units, and stopping processing;

G) where the modulo count is equal to zero, setting the acknowledgment field to indicate that the base site control unit has sent an automatic repeat request and incrementing an acknowledgment count;

H) determining whether the acknowledgment count is greater than a predetermined integer N;

I) where the acknowledgment count is less than or equal to N, broadcasting, by the base site, the slot of data including the acknowledgment field to the plurality of subscriber units, and stopping processing;

J) where the acknowledgment count is greater than N, setting a mode equal to INFO_-- MODE and broadcasting, by the base site, the slot of data including the acknowledgment field to the plurality of subscriber units, and stopping processing; and

K) where the at least first acknowledgment bit indicates that a time slot is reserved for transmission by the first subscriber unit, setting the mode to acknowledgment mode, setting the modulo count to zero, setting the acknowledgment count equal to zero, setting the acknowledgment field to acknowledgment and broadcasting, by the base site, the slot of data including the acknowledgment field to the plurality of subscriber units, and stopping processing.

4. A method for utilizing uplink channel processing at a base site for providing a contention-free access uplink channel for a first subscriber unit of a plurality of subscriber units for transmission of predetermined types of messages in a slotted communication system, comprising the steps of:

A) receiving, by a base site, a time slot of data from a subscriber unit wherein the time slot of data includes at least a first acknowledgment bit;

B) determining, by the base site, whether the time slot of data includes an acknowledgment segment;

C) where the time slot of data lacks an acknowledgment segment, transmitting, by the base site, the time slot of data to a base site control unit; and

D) where the time slot of data includes an acknowledgment segment, setting bit(s) for a mode equal to an information mode and transmitting, by the base site, the time slot of data to the base site control unit.