# US 2014/0153416 A1 · Method, wireless communication station, and system for reducing data starvation

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- Number: US 2014/0153416 A1
- Document ID: US20140153416A1
- Status: Published application
- Kind: A1
- Application number: 13/692,332
- Filed: 2012-12-03
- Published: 2014-06-05
- Earliest claimed: 2012-12-03
- Inventors: Shai Brandes; Shai Ostshega; Alexander Tolpin; Amit Bernstein
- Web page: https://patentgrep.com/patent/US20140153416A1

## CPC

- H04W 84/12: WLAN [Wireless Local Area Networks]
- H04L 1/1614: {using bitmaps}
- H04L 1/1685: {the supervisory signal being transmitted in response to a specific request, e.g. to a polling signal}
- H04L 1/1841: {Resequencing}
- H04L 1/1848: {Time-out mechanisms}
- H04L 1/1832: {Details of sliding window management}
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Embodiments of a wireless communication station and methods for reducing data starvation are generally described herein. In some embodiments, a wireless communications station passes data packets stored in a buffer to a higher-level medium access control (MAC) process, in sequential order based on a sequence number (SN) subfield of the data packets. A watchdog timer is activated upon encountering a missing data packet during the passing. Upon expiration of the watchdog timer, the wireless communication station transmits a delete block acknowledgment (DELBA) frame to terminate a block acknowledgment (ACK) agreement with an originator of the data packets.

## Claims

### Claim 1

A method to reduce data starvation in a wireless communication network, the method comprising:
passing data packets stored in a buffer to a higher-level medium access control (MAC) process, the passing being performed in a sequential order based on sequence number (SN) subfields of the data packets;
activating a watchdog timer upon encountering a missing data packet, the encountering being based on an inspection of the SN subfields during the passing; and
transmitting, upon expiration of the watchdog timer, a delete block acknowledgment (DELBA) frame to terminate a block acknowledgment (ACK) agreement with an originator of the data packets.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
receiving at least one data packet subsequent to the activation of the watchdog timer and storing the at least one data packet in the buffer;
passing data packets of the buffer to the higher-level MAC process upon expiration of the watchdog timer.

### Claim 3 (depends on 1)

The method of claim 1, wherein a duration for the watchdog timer is determined based on a latency tolerance of the higher-level MAC process.

### Claim 4 (depends on 3)

The method of claim 3, further comprising:
determining whether the buffer is empty upon encountering a missing data packet; and
wherein the activating activates the watchdog timer if the determining determines that the buffer is not empty.

### Claim 5 (depends on 3)

The method of claim 3, further comprising:
deactivating the watchdog timer if the watchdog timer is active and the determining determines that the buffer is empty.

### Claim 6 (depends on 1)

The method of claim 1, wherein the buffer of data packets is a reordering buffer configured in accordance with a standard of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards.

### Claim 7 (depends on 1)

The method of claim 1, wherein the buffer has included therein a first buffer subfield for storing an SN of a next data packet that has not been received (WinStartB); and
a second buffer subfield for indicating a highest expected SN (WinEndB); and
wherein the passing is triggered by reception of a data packet with an SN subfield corresponding to the SN stored in the first buffer subfield.

### Claim 8 (depends on 7)

The method of claim 7, further comprising:
activating the watchdog timer upon reception of a data packet with an SN subfield greater than the SN stored in the first buffer subfield and less than or equal to the SN stored in the second buffer subfield; and
passing the data packets in the buffer to the next-highest MAC process upon expiration of the watchdog timer.

### Claim 9

A wireless communication station comprising:
a medium access control (MAC) layer to configure an add block acknowledge (ADDBA) response frame;
physical layer (PHY) circuitry to
transmit the ADDBA response frame to an originator station,
receive an ADDBA request frame from the originator station, and
receive data packets from the originator station; and
one or more processors to
pass data packets to a higher-level MAC process upon receiving a data packet with an initial sequence number SN, the passing being performed in sequential order based on the SN subfields of the data packets; and
activate a watchdog timer upon encountering a missing data packet, the encountering being based on an inspection of the SN subfields during the passing.

### Claim 10 (depends on 9)

The wireless communication station of claim 9, wherein the processor is further configured to monitor the watchdog timer, and wherein the PHY layer is further configured to terminate a block acknowledgement ACK agreement with the originator station by transmitting a delete block acknowledgment (DELBA) frame to the originator station upon expiration of the watchdog timer.

### Claim 11 (depends on 10)

The wireless communication station of claim 10, wherein the PHY layer is further configured to receive additional data packets after the activation of the watchdog timer; and
the processor is further configured to
store the additional data packets in the reordering buffer; and
pass the additional data packets sequentially based on SN numbers to the next-highest MAC process upon expiration of the watchdog timer.

### Claim 12 (depends on 11)

The wireless communication station of claim 11, wherein the buffer includes a number of data packets corresponding to a size of a block ACK reception window, the reordering buffer having included therein a first buffer subfield for storing an SN of a next data packet that has not been received (WinStartB) and a second buffer subfield for indicating a highest expected SN (WinEndB).

### Claim 13 (depends on 12)

The wireless communication station of claim 12, wherein the initial SN that triggers the passing corresponds to WinStartB.

### Claim 14 (depends on 9)

The wireless communication station of claim 9, wherein the processor is further configured to store data packets received from the originator station in a buffer, the data packets including corresponding SN subfields.

### Claim 15 (depends on 14)

The wireless communication station of claim 14, wherein the processor is further configured to:
determine whether the buffer is empty upon encountering a missing data packet;
deactivate the watchdog timer if the buffer is empty; and
activate the watchdog timer if the buffer is not empty.

### Claim 16

A method for receiving aggregate medium access control service data units (A-MSDUs), the method comprising:
receiving an add block acknowledge (ADDBA) request frame requesting initiation of a block acknowledge (ACK) agreement;
transmitting an ADDBA response frame to accept initiation of the block ACK agreement; and
terminating the block ACK agreement within a time duration of detection of a missing A-MSDU during communication under the block ACK agreement.

### Claim 17 (depends on 16)

The method of claim 16, wherein the missing A-MSDU is discovered during a passing of A-MSDUs to a higher-level MAC process based on an examination, during the passing, of sequence numbers (SNs) corresponding to each of the A-MSDUs.

### Claim 18

A system comprising:
an antenna arranged to receive data packets from an originator station;
a processor arranged to
store the received data packets in a reordering buffer in a memory, the data packets including corresponding sequence number (SN) subfields,
pass the data packets of the reordering buffer to a higher-level medium access control (MAC) process upon receiving a data packet with an initial SN, the passing being performed in a sequential order based on the SN subfields of the data packets; and
activate a watchdog timer upon encountering a missing data packet, the encountering being based on an inspection of the SN subfields during the passing; and
a memory arranged to maintaining the reordering buffer, the reordering buffer including a number of data packets corresponding to a size of a block acknowledgement (ACK) reception window, the reordering buffer having included therein a first buffer subfield for storing an SN of a next data packet that has not been received (WinStartB) and a second buffer subfield for indicating a highest expected SN (WinEndB); and
wherein the initial SN that triggers the passing corresponds to WinStartB.

### Claim 19 (depends on 18)

The system of claim 18, wherein the processor is further configured to:
monitor the watchdog timer; and
terminate a block ACK agreement with the originator station by transmitting a delete block acknowledgment (DELBA) frame to the originator station upon expiration of the watchdog timer.

### Claim 20 (depends on 18)

The system of claim 18, wherein the processor is further configured to:
receive data packets after the activation of the watchdog timer;
store the data packets in the reordering buffer; and
pass the data packets to the next-highest MAC process upon expiration of the watchdog timer.

### Claim 21 (depends on 18)

The system of claim 18, wherein the processor is further configured to:
determine whether the buffer is empty upon encountering a missing data packet;
deactivate the watchdog timer if the buffer is empty; and
activate the watchdog timer if the buffer is not empty.

### Claim 22

A computer-readable medium comprising instructions that, when implemented on a receiver station, cause the receiver station to:
pass received data packets to a higher-level medium access control (MAC) process sequentially, based on sequence numbers (SNs) of the data packets;
activate a watchdog timer upon encountering a missing data packet, the encountering being based on an inspection of the SN subfields during the passing; and
terminate a block acknowledgement (ACK) agreement with an originator of the data packets by transmitting a delete block acknowledgment (DELBA) frame to the originator of the data packets.

### Claim 23 (depends on 22)

The computer-readable medium of claim 22, comprising further instructions that, when implemented on the receiver station, cause the receiver station to:
store received data packets in a reordering buffer, wherein the passing causes data packets to be emptied from the reordering buffer; and
wherein the watchdog timer is activated if the reordering buffer is not empty.

### Claim 24 (depends on 23)

The computer-readable medium of claim 23, comprising further instructions that, when implemented on the receiver station, cause the receiver station to:
receive additional data packets subsequent to activation of the watchdog timer;
store the additional data packets in the reordering buffer; and
pass the additional data packets to the higher-level MAC process upon expiration of the watchdog timer.