Method and apparatus for transmitting and receiving encoded data using multiple frequency coding

• US 5,404,374 A
• Filed: 07/12/1993
• Issued: 04/04/1995
• Est. Priority Date: 07/12/1993
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Geiger, Edward W., Mullins, Jeffery L.
• Primary Examiner(s): Cain, David C.
• Application Number:
  US08/090,886
• Time in Patent Office: 631 Days
• Field of Search: 375/1, 375/40, 371/70, 370/21
• US Class Current: 375/133
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 1/715 Interference-related aspects
• CPC Class Codes: H04B 1/7156 Arrangements for sequence synchronisation
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0082 fields explicitly indicating existence of error in data being transmitted, e.g. so that downstream stations can avoid decoding erroneous packet; relays
• CPC Class Codes: H04W 28/065 using assembly or disassembly of packets

Abstract

In a communication system including a plurality of networked stations that communicate using a slow frequency hopping system, a method for encoding a packet of data in a transmitting station and decoding the data in a receiving station. In the transmitting station, the packet is divided into data segments. Error correction segments are added to correct the data segments. The segments are fragmented into a series of fragments, and a data error control field is calculated for each fragment and appended thereto. The data units including the segments are transmitted, and in a receiving station all or a portion of the bursts are received. The DEC field for each received fragment is calculated and compared with the received DEC field to determine whether each fragment is good or bad. If there are a sufficient number of fragments in each column, then the data can be reconstructed.

Claims

1. In a communication system for networking a plurality of stations, each of which includes a transmitter and a receiver, a method for encoding a packet of data supplied by a Medium Access Control ("MAC") layer in a transmitting station that transmits said data in a series of N bursts and decoding received data units in a receiving station that receives at least one of said bursts, said method comprising the steps of:

(a) in said transmitting station, forming said packet into at least one data segment having a first data byte unit and a second data byte unit;

(b) forming an error correction (EC) segment from said data segment, said EC segment having a first EC byte unit that corrects errors in said first data byte unit and a second EC byte unit that corrects errors in the second data byte unit;

(c) fragmenting each of said data segment and EC segment into a plurality of fragments;

(d) for each fragment, calculating a data error control (DEC) field and including said DEC field in the segment associated with said fragment so that each segment together with its associated DEC fields defines a data unit ("DU");

(e) transmitting said DUs in a series of N bursts;

(f) receiving at least one of said bursts in a receiving station;

(g) utilizing the DEC field to mark each fragment in said received bursts as one of good and bad; and

(h) defining a plurality of fragment columns, each fragment column defined to include a fragment from each of said N bursts, and, for each of said fragment columns, totaling a number of good fragments, and if said number of good fragments is greater than a number (N-e) that is the minimum number of fragments necessary to reconstruct the data in the fragments of each column, then reconstructing the packet.

2. The method of claim 1, wherein said step (d), calculating a DEC field, includes calculating a random error correction field, and wherein said step (g) includes calculating the random error correction field for each received fragment, and comparing it with the received random error correction field in the DEC field associated with that fragment.

3. The method of claim 1, wherein said step (b) includes utilizing a Reed-Solomon error correction code to form said EC segment, and wherein said step (h), reconstructing the packet includes utilizing said Reed-Solomon code to correct errors in the data segment.

4. The method of claim 1, wherein said steps (e) and (f) include utilizing a slow frequency hopping system to transmit said series of bursts and to receive at least one of said bursts.

5. The method of claim 4 wherein said steps (a)-(h) are performed in said plurality of stations in the network, including performing said steps (a)-(e) in the transmitting station and performing said steps (f)-(h) in a plurality of receiving stations.

6. In a communication system for networking a plurality of stations, each of which includes a transmitter and a receiver, a method for encoding a packet of data supplied by a Medium Access Control ("MAC") layer in a transmitting station that transmits said data in a series of N bursts and decoding received data units in a receiving station that receives at least one of said bursts, said method comprising the steps of:

(a) in said transmitting station, dividing said packet into a plurality of data segments having an equal length, each having a first data byte unit and a second data byte unit;

(b) forming at least one error correction (EC) segment from said plurality of data segments, said EC segment having an equal length with said data segments, said EC segment having a first EC byte unit that corrects errors in said first data byte units and a second EC byte unit that corrects errors in the second data byte units;

(c) fragmenting each of said data segments and EC segments into a plurality of fragments;

(d) for each fragment, calculating a data error control (DEC) field and including said DEC field in the segment associated with said fragment so that each segment together with its associated DEC fields defines a data unit ("DU");

(e) transmitting said DUs in a series of N_{-- --} bursts;

(f) receiving at least one of said bursts in a receiving station;

(g) utilizing the DEC field to mark each fragment in said received bursts as one of good and bad; and

(h) defining a plurality of fragment columns, each fragment column defined by like-numbered data byte units and EC byte units from said N bursts, and, for each of said fragment columns, totaling a number of good fragments, and if said number of good fragments is greater than a number (N-e) that is the minimum number of fragments necessary to reconstruct the data in the fragments of each column, then reconstructing the packet.

7. The method of claim 6, wherein said step (d), calculating a DEC field, includes calculating a random error correction field, and wherein said step (g) includes calculating the random error correction field for each received fragment, and comparing it with the received random error correction field in the DEC field associated with that fragment.

8. The method of claim 6, wherein said step (b) includes utilizing a Reed-Solomon error correction code to form said EC segment, and wherein said step (h), reconstructing the packet includes utilizing said Reed-Solomon code to correct errors in the data segments.

9. The method of claim 6, wherein said steps (e) and (0 include utilizing a slow frequency hopping system to transmit said series of bursts and to receive at least one of said bursts.

10. The method of claim 9 wherein said steps (a)-(h) are performed in said plurality of stations in the network, including performing said steps (a)-(e) in said transmitting station and performing said steps (f)-(h) in a plurality of receiving stations.

11. A communications system for a station in a network including a plurality of stations, said communications system coupled to a computer processing unit ("CPU") in the station that provides a packet of data for transmission and receives a received packet of data, said station communicating with other stations in the network utilizing a slow frequency hopping system that transmits a series of N bursts using a plurality of N frequencies and a predetermined channel sequence, said communications system comprising:

a LAN controller including a protocol engine coupled to the CPU, said protocol engine including

(a) segmentation means for forming said packet into at least one data segment having a first data byte unit and a second data byte unit,

(b) segment error correction means for forming an error correction (EC) segment from said data segment, said EC segment having a first EC byte unit that corrects errors in said first data byte unit and a second EC byte unit that corrects errors in the second data byte unit;

(c) fragmentation means for fragmenting each of said data segment and EC segment into a plurality of fragments,

(d) DEC means for calculating a data error control (DEC) field for each fragment, and for including said DEC field in the segment associated with said fragment so that each segment together with its associated DEC fields defines a data unit ("DU"),

(e) transmitting control means for transmitting said DUs in a series of N bursts,

(f) receiving control means for receiving at least one of said bursts in a receiving station,

(g) marking means utilizing the DEC field to mark each fragment in said received bursts as one of good and bad, and

(h) reconstruction mapping means including, for each of a plurality of fragment columns defined to include a fragment from each of said N bursts, means for totaling a number of good fragments for each of said fragment columns, and if said good number is greater than a number (N-e) that is the minimum number of fragments necessary to reconstruct the data in the fragments of each column, then reconstructing the packet;

a radio frequency (RF) modem coupled to the LAN controller, including

a frequency synthesizer for producing a plurality of RF frequencies,

a RF control unit coupled to the frequency synthesizer for selecting a radio frequency,

a RF receiver,

a RF transmitter; and

an antenna coupled to said RF modem for receiving said plurality of frequencies.

12. A communications system for a station in a network including a plurality of stations, said communications system coupled to a computer processing unit ("CPU") in the station that provides a packet of data for transmission and receives a received packet of data, said station communicating with other stations in the network utilizing a slow frequency hopping system that transmits a series of N bursts using a plurality of N frequencies and a predetermined channel sequence, said communications system comprising:

a LAN controller including a protocol engine coupled to the CPU, said protocol engine including

(a) segmentation means for dividing said packet into a plurality of data segments having an equal length, each having a first data byte unit and a second data byte unit,

(b) segment error correction means for forming at least one error correction (EC) segment from said plurality of data segments, said EC segment having an equal length with said data segments, said EC segment having a first EC byte unit that corrects errors in said first data byte units and a second EC byte unit that corrects errors in the second data byte units,

(c) fragmentation means for fragmenting each of said data segments and EC segments into a plurality of fragments,

(d) DEC means for calculating a data error control (DEC) field for each fragment, and for including said DEC field in the segment associated with said fragment so that each segment together with its associated DEC fields defines a data unit ("DU"),

(e) transmission control means for transmitting said DUs in a series of N bursts,

(f) reception control means for receiving at least one of said bursts in a receiving station,

(g) marking means utilizing the DEC field to mark each fragment in said received bursts as one of good and bad, and

(h) reconstruction mapping means including, for each of a plurality of fragment columns defined by like-numbered data byte units and EC byte units from each of said N bursts, means for totaling a number of good fragments for each of said fragment columns, and if said good number is greater than a number (N-e) that is the minimum number of fragments necessary to reconstruct the data in the fragments of each column, then reconstructing the packet;

a radio frequency (RF) modem coupled to the LAN controller, including

a frequency synthesizer for producing a plurality of RF frequencies,

a RF control unit coupled to the frequency synthesizer for selecting a radio frequency,

a RF receiver,

a RF transmitter; and

an antenna coupled to said RF modem for receiving said plurality of frequencies.