MobileMAN Hardware development for the MAC module current state and outlook IAB meeting By

Apu, IDe, 2004.06.07 MobileMAN meeting, Helsinki Page 1/18

MobileMAN Hardware development for the MAC module

current state and outlookIAB meeting

By

Ralph Bernasconi, Ivan Defilippis, Silvia Giordano, Alessandro Puiatti

SUPSI Manno

Helsinki, June 7-8 2004


Contents

• Introduction• Completed work• Current work• Next steps• Data structure description• Questions?


IntroductionProject’s SUPSI-DIE goals (reminder)

• Provide flexible development- and test-bed for enhanced WLAN protocol (CNR)

• Bursty responsive MAC• Better contention scheme (backoff); avoid collisions even

for dense and active networks• Ensure compatibility with 802.11x

• Provide few samples to partners• Provide inputs for new standard


• Analysis of the Market for the 802.11 implementations• Available solutions?• Which solution best suits our needs? Criteria are:

- Cost- Reliability- Flexibility- Access to the software code- Access to the firmware- Easy development environment- Secure and prompt technical support

Completed work (1/8)


• Alternatives for development: • Start from scratch:

- Implementation of a complete chain: MAC - BB - RF

• Start “in the middle”:- Implementation of the MAC only

• Start from an already implemented solution:- Change software and firmware for our purpose



• Selected solution

• Start “in the middle”

• BB and RF already developed by Elektrobit AG:

- DT20 Modem (Intersil Prism-I chipset)

• Implement MAC on a DSP microcontroller

- TI C6713 board (Texas Instruments)



Level-Switch interfaces

DT20 - Modems

TI C6713 boards

JTAG interface

• Development system





• Deep analysis of the 802.11 standard• Procedures and flowchart for the Tx/Rx further implementation

• Implementation on the DSP board• CRC on FPGA• Tx/Rx between MAC and BB• Channel Sensing mechanism on MAC (MAC – RF)• MAC Tx mechanism• MAC Rx mechanism



• Implementations on the DSP board (cont.)• Standard backoff mechanism• Regular 802.11 frame generation• Fragmented frame generation• RTS/CTS/DATA/AK handshake• MAC Address recognition• Channel contention



• Tests done (2 systems/boards)• Stress tests in Tx between boards connected by cable• Stress tests in Rx between boards connected by cable• Stress tests in Tx/Rx between boards connected by cable• Stress tests in Tx/Rx between boards in wireless mode

- Standard backoff tested successfully- Fragmented Tx/Rx tested successfully- RTS/CTS/DATA/AK handshake tested successfully



• Assembly of the 3rd system/board• Definition of the host interface mechanism

(via IEEE-1394/FireWire)• Definition of the standard packets data-structure• Definition of data-structure extensions for cross-

layering implementation

Current work


• Implementation on the DSP• NAV (Network Allocation Vector)

• Test of a 3 nodes network (with above functionality)• Implementation and test of the host interface mechanism• Implementation and test of the standard packets data-structure• Implementation and test of data-structure extensions for cross-

layering• Implementation and test of the modified (CNR-Pisa) backoff

mechanism

Next steps


• Memory slotted in parameterized slot length (default frame max length)

• Descriptor mechanism for handling data• Different queues for managing data transfer:

• From MAC to PHY and from PHY to MAC• From MAC to Host and from Host to MAC

• Implementation of priority mechanisms for each queue• Control flags in descriptor in which:

• DATA = Frame• DATA = parameters for/from cross-layering

Data Structure description (1/4)


MAC header x

FCS x

Frame

Memory Data Area

MAC(DSP)

Frame body x+1

Frame body x

Descriptor x

Descriptorx+1

End HMQ

Descriptor x+n+1

MAC h. y+n-1

Frame body y+n-1

FCS y+n-1

MAC h. y+n

Frame body y+n

FCS y+n

Descriptorx+n

Frame body x+n

Frame body x+n+1Descriptor y+n-1

Descriptory+n

End MPQ

MAC to PHY Queue

BeginHost to MAC

Queue

BeginHost to MAC

Queue

End MPQ

End HMQ

MAC h. y+n+1

FCS y+n+1

Frame body y+n+1

Descriptor y+n+1



MAC header y

FCS y

Frame

Memory Data Area

MAC(DSP)

Frame body x+1

Frame body x

Descriptor x

Descriptorx+1

End MHQ

MAC h. y+1

Frame body y+1

FCS y+1

MAC h. y+2

Frame body y+2

FCS y+2

Descriptorx+n

Frame body y

Descriptory+2

Descriptor y+1

End PMQ

PHY to MAC Queue

BeginMAC to Host

Queue

Begin

Descriptor y

Frame body x+n

End MHQ

PHY to MAC Queue

Begin

Frame body x+n+1

Descriptor x+n+1



Management of queues with different levels of priority

Descriptor 1Pn

Descriptor 1Pn-1

End Q

DescriptorP0

Descriptor 2Pn

Descriptor 3Pn

Descriptor 4Pn

Descriptor kPn

End Q-PnDescriptor 2

Pn-1Descriptor h

Pn-1End Q-Pn-

1

Descriptor 2P0

Descriptor 3P0

Descriptor gP0

End Q-P0



• Questions?• Thanks for your attention!

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MobileMAN Hardware development for the MAC module current state and outlook IAB meeting By