Enhancing fragmentation and defragmentation procedures in broadband wireless networks

• US 8,630,245 B2
• Filed: 09/23/2010
• Issued: 01/14/2014
• Est. Priority Date: 11/06/2009
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Venkatachalam, Muthaiah, Yang, Xiangying, Bergman, Aran, Mohanty, Shantidev
• Primary Examiner(s): Kang, Suk Jin
• Application Number:
  US12/889,346
• Publication Number:
  US 20110110343A1
• Time in Patent Office: 1,209 Days
• Field of Search: None
• US Class Current: 370/329
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 9/0838 Key agreement, i.e. key establishment technique in which a shared key is derived by parties as a function of information contributed by, or associated with, each of these network architectures or network communication protocols for key exchange in a packet data network H04L63/061
• CPC Class Codes: H04L 9/3273 for mutual authentication network architectures or network communication protocols for achieving mutual authentication in a packet data network H04L63/0869
• CPC Class Codes: H04W 12/062 Pre-authentication
• CPC Class Codes: H04W 36/0038 of security context information
• CPC Class Codes: H04W 36/0061 of neighbour cell information
• CPC Class Codes: H04W 36/0066 of control information between different types of networks in order to establish a new radio link in the target network
• CPC Class Codes: H04W 48/10 using broadcasted information

Abstract

A preemption system enables successful transmission of multiple service data units (SDUs) across a wireless interface. The preemption system addresses out-of-order transmissions of fragments of SDUs, such that the receiver is able to process each successfully. The preemption system enables a higher-priority SDU to simultaneously be transmitted with a lower-priority SDU, so that delays in processing the lower-priority SDU does not negatively affect processing of the higher-priority SDU. The preemption system also addresses non-automatic repeat request medium access controller (non-ARQ MAC) connections that only use hybrid automatic repeat request (HARQ), in which the HARQ transmission may cause out-of-order delivery of SDU fragments.

Claims

1. A fragmentation state machine in a transmitter, the fragmentation state machine comprising:

a fragmentation characterization engine to;

generate a header for each fragment of a first service data unit (SDU), the first SDU comprising a plurality of fragments, the first SDU having a flow identifier (ID) indicating a first medium access channel (MAC)/flow connection, the header of each fragment comprising;

a first channel ID to indicate a first fragmentation channel through which the fragment of the first SDU is transmitted;

a sequence ID indicating a numerical location of the fragment in the first SDU; and

a fragmentation extension ID indicating whether the fragment is a first fragment, a last fragment, or a middle fragment of the first SDU, or whether the first SDU is unfragmented; and

generate a second header for each fragment of a second SDU, the second SDU comprising a plurality of fragments and the same flow ID as the first SDU, the second header of each fragment of the second SDU comprising;

a second channel ID to indicate a second fragmentation channel through which the fragment of the second SDU is transmitted;

a sequence ID indicating a relative numerical location of the fragment in the second SDU; and

a fragmentation extension ID indicating whether the fragment is a first fragment, a last fragment, or a middle fragment of the second SDU, or whether the second SDU is unfragmented;

wherein the fragments of the first and second SDUs are wirelessly transmitted on separate fragmentation channels of the same MAC/flow connection to a receiver.

2. The fragmentation state machine of claim 1, wherein transmission of the second SDU is initiated on the second fragmentation channel before transmission of the first SDU is completed on the first fragmentation channel.

3. The fragmentation state machine of claim 2, wherein the second SDU has a higher priority than the first SDU.

4. The fragmentation state machine of claim 1, wherein the flow ID is obtained from a field of a generic MAC header preceding each fragment.

5. The fragmentation state machine of claim 1, wherein the channel ID, the sequence ID, and the fragmentation extension ID are fields in a fragmentation and packing extension header preceding each fragment, the fragment comprising data.

6. The fragmentation state machine of claim 1, wherein the channel ID, the sequence ID, and the fragmentation extension ID are fields in a fragmentation extension header preceding each fragment, the fragment comprising management information.

7. A defragmentation state machine in a receiver, the defragmentation state machine comprising:

means to decode a header of each fragment of either a first service data unit (SDU) or a second SDU, wherein the first SDU is received wirelessly from a transmitter on a first fragmentation channel and the second SDU is received wirelessly from the transmitter on a second fragmentation channel, the first SDU comprising a flow ID and second SDUs comprising the same flow ID, each header comprising;

a channel ID, wherein the first SDU channel ID header indicates the first fragmentation channel and the second SDU channel ID header indicates the second fragmentation channel;

a sequence ID indicating a numerical location of the fragment in its respective SDU; and

a fragmentation extension ID indicating whether the fragment is a first fragment, a last fragment, or a middle fragment of the respective SDU, or whether the respective SDU is unfragmented;

a first buffer to receive fragments received on the first fragmentation channel;

a second buffer to receive fragments on the second fragmentation channel, wherein the channel ID operates as an index into the buffers of the receiver;

wherein the receiver, despite receiving the fragments of the first and second SDU out of order, is able to decode the first SDU and the second SDU using the header of each fragment.

8. The defragmentation state machine of claim 7, wherein the flow identifier indicates the MAC/flow connection through which the fragment is wirelessly received from the transmitter.

9. The defragmentation state machine of claim 8, further comprising:

a first discard timer to keep track of fragments stored in the first buffer, wherein all fragments of the first SDU are received before the first SDU is decoded; and

a second discard timer to keep track of fragments stored in the second buffer, wherein all fragments of the second SDU are received before the second SDU is decoded.

10. The defragmentation state machine of claim 8, wherein the flow identifier is obtained from a field of a generic MAC header preceding each fragment.

11. The defragmentation state machine of claim 9, wherein the fragmentation extension ID, the channel ID, and the sequence ID are obtained from fields in a fragmentation and packing extension header preceding each fragment of a service data unit comprising data.

12. The defragmentation state machine of claim 9, wherein the fragmentation extension ID, the channel ID, and the sequence ID are obtained from fields in a fragmentation extension header preceding each fragment of a service data unit comprising management information.

13. The defragmentation state machine of claim 9, wherein the first buffer is emptied if the first discard timer expires before all fragments of the first service data unit are received from the transmitter.

14. The defragmentation state machine of claim 9, wherein the second buffer is emptied if the second discard timer expires before all fragments of the second service data unit are received from the transmitter.

15. The defragmentation state machine of claim 9, wherein the first discard timer has a value based on a maximum delay time for a protocol data unit.

16. A transceiver, comprising:

a transmitter comprising a fragmentation state machine, the fragmentation state machine to;

separately characterize each fragment of a service data unit (SDU) by adding a header to the fragment before transmission; and

send fragments of two distinct SDUs over different fragmentation channels to a remote receiver, wherein the two distinct SDUs share a flow identifier (ID); and

a receiver comprising a defragmentation state machine, the defragmentation state machine to;

store each fragment received from a remote transmitter into one of a plurality of buffers, with the selected storage buffer being based on a channel ID of the fragment, until either all fragments of a service data unit associated with that fragmentation channel are received or a discard timer expires; and

for each buffer, identify the characterized fragments of the service data unit associated with the fragmentation channel and reorder them if needed.

17. The transceiver of claim 16, wherein the one or more headers comprise the following fields:

a flow identifier field to indicate the MAC/flow connection of the associated SDU;

a fragment control field to indicate whether the fragment is one of several fragments and, if so, whether the fragment is a first fragment, a last fragment, or a middle fragment;

a channel identifier field to specify the fragmentation channel through which the fragment is to be wirelessly transmitted to the remote receiver; and

a sequence identifier field to characterize the fragment as either a first fragment, a last fragment, or a middle fragment of the respective SDU, or whether the respective SDU is unfragmented.

18. The transceiver of claim 16, wherein the defragmentation state machine discards the contents of the buffer storing the fragments without decoding the respective SDU if the discard timer expires.

19. The transceiver of claim 17, wherein the flow identifier field is part of a generic MAC header and the fragment control field, the channel identifier field, and the sequence identifier field are part of a fragmentation and packing extension header of a data packet.

20. The transceiver of claim 17, wherein the flow identifier field is part of a generic MAC header and the fragment control field, the channel identifier field, and the sequence identifier field are part of a fragmentation extension header of a management packet.