November 2004 Shaomin Mo, Panasonic -- PDNL Slide 1 IEEE 802.15-04/0620r0 Submission Project: IEEE P802.15 Working Group for Wireless Personal Area N Project: IEEE P802.15 Working Group for Wireless Personal Area N etworks ( etworks ( WPANs WPANs ) ) Submission Title: [Schemes and Design to Enhance Retransmission for 802.15.3 Systems] Date Submitted: [11 November, 2004] Source: [Shaomin Mo] Company [Panasonic -- PDNL] Address [Two Research Way, Princeton, New Jersey, USA] Voice:[609-734-7592], FAX: [609-987-8827], E-Mail:[[email protected]] Re: [] Abstract: [This document proposes a scheme to enhance performance of retransmission for 802.15.3 ] Purpose: [This document is provided in support of 802.15.3b activities.] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.
Transcript
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 1
IEEE 802.15-04/0620r0
Submission
Project: IEEE P802.15 Working Group for Wireless Personal Area NProject: IEEE P802.15 Working Group for Wireless Personal Area Networks (etworks (WPANsWPANs))
Submission Title: [Schemes and Design to Enhance Retransmission for 802.15.3 Systems]Date Submitted: [11 November, 2004]Source: [Shaomin Mo] Company [Panasonic -- PDNL]Address [Two Research Way, Princeton, New Jersey, USA]Voice:[609-734-7592], FAX: [609-987-8827], E-Mail:[[email protected]]Re: []
Abstract: [This document proposes a scheme to enhance performance of retransmission for 802.15.3 ]
Purpose: [This document is provided in support of 802.15.3b activities.]Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 2
IEEE 802.15-04/0620r0
Submission
Schemes and Design to Enhance Retransmission for 802.15.3 Systems
Shaomin Mo
Panasonic Digital Networking Laboratory
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 3
IEEE 802.15-04/0620r0
Submission
Outline
• CE requirements for home theater applications• Signal processing in wireless systems• Current 802.15.3 PHY & MAC• Proposed scheme & design• Summary• Conclusion
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 4
IEEE 802.15-04/0620r0
Submission
CE Requirement for Home Theaters
• Home Theatre CE applications require very low error rates (e.g. one MPEG packet loss in >2 hours)
• Benchmark packet size and Packet Error Rate (PER) values for UWB PHY evaluation (1024 byte and PER 8%) may be too high for such CE applications
• Retransmission is unavoidable to achieve PER goal
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 5
IEEE 802.15-04/0620r0
Submission
Signal Processing in Wireless Systems
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 6
IEEE 802.15-04/0620r0
Submission
Signal Processing in Wireless Systems
Descrambler DemodulatorDemapperFEC Decoder
Source Data
Transmitter (Tx)
Receiver (Rx)
Scrambler ModulatorConstellation Mapper
FEC Encoder
Source Data
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 7
IEEE 802.15-04/0620r0
Submission
Multiple Antenna at Rx to Increase SNR – 1
• Combination of– Two frames can get about 3dB gain– Three frames about 4.7dB– Four frames about 6dB
• Condition for combination– Same data
• Combination can be performed at different blocks in Rx– Combined at demapper – same modulation at transmitter– Combined at decoder – same encoder at transmitter
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 8
IEEE 802.15-04/0620r0
Submission
Multiple Antenna at Rx – 2
Multiple demodulators combined at demapper
Descrambler
Demodulator
DemapperFEC Decoder
Source Data
Demodulator
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 9
IEEE 802.15-04/0620r0
Submission
Multiple Antenna at Rx – 3
Multiple demodulators and demappers combined at FEC decoder
Descrambler
Demodulator
Demapper
FEC Decoder
Source Data
Demodulator
Demapper
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 10
IEEE 802.15-04/0620r0
Submission
Retransmission
• Retransmission can be considered & treated as multiple antennas
• Original & retransmitted frames can be combined to increase SNR
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 11
IEEE 802.15-04/0620r0
Submission
Current 802.15.3 PHY & MAC
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 12
IEEE 802.15-04/0620r0
Submission
Block ACK – Dly-ACK
M1-
F1 D
ly-A
CK
XX
M1-
F1 D
ly-A
CK
M2-
F1 D
ly-A
CK
M2-
F2 D
ly-A
CK
M2-
F3 D
ly-A
CK
M1-
F3 D
ly-A
CK
Req
M1-
F2 D
ly-A
CK
X
M2-
F4 D
ly-A
CK
Req
M1-
F 2,
3
M2-
F4 D
ly-A
CK
Req
X X
Source device data transmission
Destination device Dly-ACK
responses
X indicates HCS or FCS
check failure at receiver
M1-
F 2,
3
M1-
F3 D
ly-A
CK
Req
M2-
F 2,
3,4
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 13
IEEE 802.15-04/0620r0
Submission
Problem for Combined Demodulation• Scrambler is controlled by PHY
– The 15-bit seed value chosen shall correspond to the seed identifier. The seed identifier value is set to 00 when the PHY is initialized and is incremented in a 2-bit rollover counter for each frame that is sent by the PHY. In other words, seeds are chosen incrementally and circularly.
• Retransmission is controlled by MAC
• Retransmitted frames may be scrambled with different scramblers
• Bit stream after scramblers from same frame may be different
• Different bit streams cannot be combined in demodulation
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 14
IEEE 802.15-04/0620r0
Submission
Proposed Scheme & Design
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 15
IEEE 802.15-04/0620r0
Submission
1 – New Scrambler Setting
• Besides of using increment and circular seed setting, the retransmitted frames are assigned with the same scrambler seeds as the originally transmitted frames.
• In addition to the same scrambler setting, the retransmitted frames are encoded with the same encoder, as the originally transmitted frames.
• Doing these results in same payload, which makes it possible for combined demodulation in receivers.
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 16
IEEE 802.15-04/0620r0
Submission
1 – New Scrambler Setting
• To accomplish these functions, scrambler setting should be controlled by MAC
• To make it clear, following statement (or similar) should be added into both “retransmission” in MAC and “scrambler” in PHY– scrambler seed is assigned by MAC and retransmitted
frames have same scrambler seeds as those in originally transmitted frames
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 17
IEEE 802.15-04/0620r0
Submission
2 – Demodulation of Header
• One task of header demodulation is to get parameters from PHY header necessary to demodulate payload data, i.e., – Seed identifier of scrambler– Data rate of MAC frame body– Payload length
• Same data & same scrambler seed & same rate same payload length
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 18
IEEE 802.15-04/0620r0
Submission
2 – Demodulation of Header
• If payload is modulated using the same parameters• If multiple headers are received
• Only one header is required to be demodulated to get PHY Header
• Due to the small size, headers can be demodulated many time in one frame time
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 19
IEEE 802.15-04/0620r0
Submission
2 – Demodulation of Header
Retransmitted frame(HCS checking)
Original transmitted frame(HCS checking)
11 10
01 00
• In cases of 11, 10 & 01, try header demodulation until one header is correctly extracted
• In cases of 00, after above try, combined demodulation can be performed
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 20
IEEE 802.15-04/0620r0
Submission
3 – Frame Numbering
• Another task of header demodulation is to get frame number – MSDU number and Fragment number – for packet assembly at MAC layer
• In order to combine frames, we need to identify frames with the same frame numbers
• However frame number can also be “extracted” as long as the following rule is used– Frames including retransmitted frames are transmitted in
sequential order in bursts– MSDU(i) is sent before MSDU(j) if i<j– Fragment(m) is sent before Fragment(n) if i=j & m<n
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 21
IEEE 802.15-04/0620r0
Submission
3 – Frame Numbering
M1-
F1 D
ly-A
CK
M1-
F2 D
ly-A
CK
M2-
F1 D
ly-A
CK
M2-
F2 D
ly-A
CK
X
M2-
F3 D
ly-A
CK
Req
X
S o u r c e d e v ic e d a ta
t r a n s m is s io n
X in d ic a te s H C S c h e c k
fa i lu r e a t r e c e iv e r
Originally transmitted frames
• Unknown order• Backward
• From the 4th frame with ‘MSDU2 Fragment 2’, we can deduce the previous frame is ‘MSDU2 Fragment 1’;
• Since there is no frame with ‘Fragment 0’, the 2nd frame must be ‘MSDU 1’;• From the first frame with ‘MSDU 1 Fragment 1’, we can deduce that the second
frame should be either ‘MSDU 1 Fragment 2’ or ‘MSDU 2 Fragment 1’. Based on previous deduction, we can conclude that the second frame is ‘MSDU 1 Fragment 2’.
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 22
IEEE 802.15-04/0620r0
Submission
3 – Frame Numbering
M1-
F1 D
ly-A
CK
M1-
F2 D
ly-A
CK
M2-
F1 D
ly-A
CK
M2-
F2 D
ly-A
CK
X
M2-
F3 D
ly-A
CK
Req
X
S o u r c e d e v ic e d a ta
t r a n s m is s io n
X in d ic a te s H C S c h e c k
fa i lu r e a t r e c e iv e r
Retransmitted frames
• Known order• Forward
• From the 1st frame with ‘MSDU1 Fragment 1’, we can deduce the next frame will be ‘MSDU1 Fragment 2’;
• The 3rd frame will be ‘MSDU 2 Fragment 1’.
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 23
IEEE 802.15-04/0620r0
Submission
4 – Header
Octets:1
Stream Index
213 1 2
Frame ControlPNIDDestIDSrcIDFragmentation Control
Bits: b15-b11
Reserved
b6
ACK policyRetryMore Data
b10 b8-b7b9
SEC Protocol Version
Frame Type
b5-b3 B2-b0
Beacon frameImm-ACK frameDly-ACK frame
Command frameData frameReserved
000001010011100
110-111
Frame typeb5-b3b8-b7 ACK policy type
00011011
No ACKImmediate ACK
Burst ACKBurst ACK Request
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 24
IEEE 802.15-04/0620r0
Submission
4 – Header
• ‘Retry’ bit makes headers in original frames and retransmitted frames different
• Remove ‘retry’ bit or leave it unprotected to make same header
• Same header makes combined demodulation of header possible
• Caution: there won’t be two different frames with the same MSDU number in one burst
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 25
IEEE 802.15-04/0620r0
Submission
5 – Demodulation of Payload
• If payload is modulated using the same parameters• If multiple frames are received
• Due to limitation of processing power, payload can be demodulated only one time in one frame time
• Combined demodulation can be used
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 26
IEEE 802.15-04/0620r0
Submission
Complicity Analysis
• Little change to current PHY & MAC specification
• Slightly extra processing for payload data• A little more processing for header• Memory to store frames
• Low-end devices– No extra memory for data storage– Do not store frames– Perform demodulation on single frame
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 27
IEEE 802.15-04/0620r0
Submission
Summary
• MAC controlled scrambler setting– Scrambler seed is assigned by MAC and retransmitted
frames have same scrambler seeds as those in originally transmitted frames
• Frames including retransmitted frames are transmitted in order in bursts– Frames including retransmitted frames are transmitted in
sequential order in bursts
November 2004
Shaomin Mo, Panasonic -- PDNLSlide 28
IEEE 802.15-04/0620r0
Submission
Conclusion
• A new scheme & design is proposed to enhance performance of retransmission in block ACK
• The scheme causes little change for current 802.15.3 PHY & MAC
• Backward compatible to devices with traditional demodulation
