US 6,665,298 B1Granted

Reassembly unit and a method thereof

AssigneeMotorola, Inc.

InventorsEran Kirzner, Yuval Lachman, Avi Hagai, Itai Katz

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Abstract

A reassembly unit comprising of a reassembly buffer and a control unit and a detector. The reassembly unit monitors an amount of data AMD stored in the reassembly register and compares AMD to four thresholds, TS1, TS2, TS3 and TS4. TS1 and TS4 define the size of the reassembly buffer. TS2 defines the delay of reassembly unit 40. A difference between TS1 and TS2 defines an underflow recovery period in which data is not read out of the buffer. A difference between TS4 and TS3 define an overflow recovery period in which data is not written in the buffer. The four thresholds can be changed during an operation of the reassembly unit, allowing a user to adjust the thresholds according to the state of the reassembly unit.

Claims22

Dependent claims

A reassembly unit adapted to receive data cells from a first communication channel, temporarily store the received data and to provide data cells to a second communication channel, in a manner that compensates for timing differences between a reception of data cells from the first communication channel and a provision of data cells to the second communication channel, the reassembly unit comprising:

a buffer, adapted to receive data cells from the first communication channel and to provide data cells to the second communication channel, according to control signals provided by a control unit;
a detector, coupled to the buffer, the detector is adapted to detect AMD, AMD reflecting an amount of data cells stored in the buffer, compare AMD to four thresholds and generate status signals reflecting a relationship between AMD and the four thresholds TS1, TS2, TS3 and TS4, TS1<TS2<TS3<TS4;
and
a control unit, coupled to the buffer and to the detector, for receiving the status signal and for controlling an access to the buffer;
wherein
(One) if AMD<TS1 the control unit prevents a data cells from being read out of the buffer and allows data cells to be written in the buffer;
(Two) while AMD remains in a range of TS1<AMD<TS2 after reaching TS1, the control unit prevents data cells from being read out of the buffer and allows data to be written in the buffer;
(Three) if AMD≧TS4 the control unit prevents data cells from being written in the buffer and allows data cells to be read out of the buffer;
(Four) while AMD remains in a range of TS3<AMD<TS4 after reaching TS4 the control unit prevents data cells from being written in the buffer and allows data cells to be read out of the buffer, and
(Five) if TS2≦AMD≦TS3 control unit allows data cells to be written to the buffer and allows data cells to be read out of the buffer.

7 more elements

a plurality of data buffers, adapted to receive data cells from the first communication channel and to provide data cells to the second communication channel, according to control signals provided by a control unit;
a reassembly buffer, adapted to store a plurality of buffer descriptors, a buffer descriptor has a pointer that points to a data buffer in which data cells are written in and read out of;
a detector, adapted to detect AMD, AMD reflecting an amount of data cells stored in the plurality of the data buffers, compare AMD to four thresholds and generate status signals reflecting a relationship between AMD and the four thresholds TS1, TS2, TS3 and TS4, TS1<TS2<TS3<TS4;
and
a control unit, coupled to the plurality of data buffers, to the reassembly buffer and to the detector, for receiving the status signal and for controlling an access to the plurality of data buffers;
wherein
(One) if AMD≦TS1 the control unit prevents a data cells from being read out of the plurality of data buffers and allows data cells to be written in the buffer;
(Two) while AMD remains in a range of TS1<AMD<TS2 after reaching TS1, the control unit prevents data cells from being read out of the plurality of data buffers and allows data to be written in the plurality of the data buffers;
(Three) if AMD≧TS4 the control unit prevents data cells from being written in the plurality of data buffers and allows data cells to be read out of the plurality of data buffers;
(Four) while AMD remains in a range of TS3<AMD<TS4 after reaching TS4 the control unit prevents data cells from being written in the plurality of the data buffers and allows data cells to be read out of the plurality of the data buffers;
and
(Five) if TS2≦AMD≦TS3 the control unit allows data cells to be written to the plurality of data buffers and allows data cells to be read out of the plurality of the buffers.

9 more elements

A reassembly unit adapted to receive data cells from a first communication channel, temporarily store the received data and to provide data cells to a second communication channel, in a manner that compensates for differences between a transmission rate of the first communication channel and a reception rate of the second communication channel, the reassembly unit comprising:

a buffer, coupled to the first and the second communication channels;
a detector, coupled to the buffer, the detector is adapted to detect an amount AMD of data stored within the buffer, compare this amount to four thresholds and generate status signals reflecting a relationship between AMD and the four thresholds TS1, TS2, TS3 and TS4, TS1<TS2<TS3<TS4;
and
a control unit, coupled to the buffer and the detector, for receiving the status signal and for controlling an access to the buffer;
wherein the control unit allows data cells to be written to and read from the buffer, wherein:
(One) the control unit prevents data cells from being read from the buffer during a underflow and an underflow recovery period, an underflow occurs when AMD=TS1, an underflow recovery period occurs between a moment in which an underflow ends and a moment in which AMD first reaches TS2;
(Two) the control unit prevents data cells from being written to the buffer during an overflow and an overflow recovery period, a overflow occurs when AMD=TS4, an overflow recovery period occurs between a moment in which an overflow ends and a moment in which AMD first reaches TS3;
and
(Three) else, the control unit allows data cells to be written to and be read from the buffer.

6 more elements

A method for reassembling data cells, the data cells being received from a first communication channel, are stored and transmitted to a second communication channel in a manner that compensates for timing differences between a reception of data cells from the first communication channel and a provision of data cells to the second communication channel, the method comprising the steps of:

(a) initializing a reassembly unit, resetting a variable AMD, AMD reflecting an amount of data cells stored within a reassembly unit;
(b) checking a relationship between AMD and four thresholds TS1, TS2, TS3 and TS4;
wherein
(1) if AMD≦TS1 preventing data cells from being read out of the reassembly unit and allowing data cells to be written in the buffer, updating AMD and jumping to step 18(b);
(2) while AMD remains in a range of TS1<AMD<TS2 after reaching TS1, preventing data cells from being read out of the reassembly unit and allowing data cells to be written in the buffer;
updating AMD and jumping to step 18(b);
(3) if AMD≧TS4 preventing data cells from being written in the reassembly unit and allowing data cells to be read out of the reassembly unit;
updating AMD and jumping to step 18(b);
(4) while AMD remains in a range of TS3<AMD<TS4 after reaching TS4, preventing data cells from being written in the reassembly unit and allowing data cells to be read out of the reassembly unit;
updating AMD and jumping to step 18(b);
and
(5) if TS2≦AMD≦TS3 allowing data cells to be written to the reassembly unit and allowing data cells to be read out of the reassembly unit;
updating AMD and jumping to step 18(b).

10 more elements

Dependencies are inferred from the claim text.