`(12) Patent Application Publication (10) Pub. No.: US 2007/0064669 A1
`(43) Pub. Date: Mar. 22, 2007
`
`Classon et al.
`
`US 20070064669A1
`
`(54) METHOD AND APPARATUS FOR
`REDUCING ROUND TRIP LATENCY AND
`OVERHEAD WITHIN A COMMUNICATION
`SYSTEM
`
`(21)
`
`App]. No.:
`
`11/276,982
`
`(22)
`
`Filed:
`
`Mar. 20, 2006
`
`(75)
`
`Inventors: Brian K. Classon, Palatine, IL (US);
`Kevin L. Baum, Rolling Meadows, IL
`(US); Amitava Ghosh, Buifalo Grove,
`IL (US); Robert T. Love, Barrington,
`IL (US); Vijay Nangia, Algonquin, IL
`(US); Kenneth A. Stewart, Grayslake,
`IL (US)
`
`Correspondence Address:
`MOTOROLA, INC.
`1303 EAST ALGONQUIN ROAD
`IL01/3RD
`SCHAUMBURG, IL 60196
`
`Related US. Application Data
`
`(60)
`
`Provisional application No. 60/666,494, filed on Mar.
`30, 2005.
`
`Publication Classification
`
`Int. Cl.
`
`H043
`US. Cl.
`
`(2006.01)
`7/212
`........................... 370/347; 370/337; 709/236
`
`ABSTRACT
`
`(51)
`
`(52)
`
`(57)
`
`During operation radio frames are divided into a plurality of
`subframes. Data is transmitted over the radio frames within
`
`(73) Assignee:
`
`MOTOROLA,
`(US)
`
`INC., Schaumburg,
`
`IL
`
`a plurality of subframes, and having a frame duration
`selected from two or more possible frame durations.
`
`701701
`
`702
`RADIO FRAME CONSTRUCTED FROM SHORT FRAMES
`
`
`
`
`
`RADIO FRAME n
`
`
`RADIO FRAME n+1
`
`
`RADIO FRAME (10ms) \
`
`
`
` RADIO FRAME n--1
`SYNCHRONISATION AND
`CONTROL REGION //
`
`/’
`
`RADIO FRAME CONSTRUCTED FROM LONG FRAMES
`
`\
`
`V 7
`
`LONG FRAME
`
`03
`
`E CONTROL SYMBOL
`
`SAMSUNG 1015
`
`SAMSUNG 1015
`
`1
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 1 0f 19
`
`US 2007/0064669 A1
`
`
`
`FIG. 1
`
`@
`
`TRANSMITTER
`
`RECEIVER
`
`2
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 2 0f 19
`
`US 2007/0064669 A1
`
`
`RADIO FRAME (10m5)
`
`
`
`Tsf
`// SUB—FRAME
`\
`P 0an SYMBOLS
`
`
`/
`
`Tsn
`
`Tsf
`
`\
`
`\
`
`Nrf
`
`sus—FRAMES
`
`FIG. 3
`M
`
`SYMBOLS
`
`SCHEDULABLE
`UNIT
`
`SHORT FRAME MULTIPLEX
`
`
`
`
`
`
`
`
`
`
`
`
`
`AL
`
`
`IIIIIIIIV‘IIIIIIIIV‘IIIIIIII.\\\\\\\II/I .\\\\\\(III
`1;
`
`
`
`
`
`0.5ms
`0.5ms
`0.5ms
`
`
`SHORT FRAME
`ICOMMON PILOT
`(0i5ms)
`ECONTROL
`El DATA
`
`
`
`FIG- 4
`
`3
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 3 0f 19
`
`US 2007/0064669 A1
`
`SCHEDULABLE
`UNIT
`
`\
`
`LONG FRAME MULTIPLEX
`
`V///
`
`7//////
`
`//////M
`
`//////A
`
`7/?Z///////4I//
`
`//
`
`//
`
`//I////////
`
`
`
`////H/////
`
`/////
`
`
`
`//////////
`
`V/a/A
`
`w////
`
`/////IIV/é
`
`
`
`//////w//.///
`
`
`
`/////////////
`
`//
`
`//
`
`//
`
`//IZ;
`
`//w////
`
`V/////Ag////u
`
`//
`
`/////
`
`/////I//
`
`V/////
`
`////
`
`////
`
`////////
`
`//
`
`V////
`
`
`
`///.///VW/////A
`
`(Sims)
`
`D OOMMOM PILOT SYMBOL
`
`E CONTROL SYMBOL
`
`0 DATA SYMBOL
`
`FIG.
`
`5
`
`PARAMETER
`
`NoITARUGIFN0CEMARFGN0L
`
`RADIO FRAME DURATION [RBI-E0-
`SUBFRAMES / RADIO FRAME
`[1-0-0
`SUBFRAME DURATION ms
`SUBFRAMES / LONG FRAME
`LOMO FRAME DURATIOM ms
`W
`OVERHEED SUBFRAMES
`-
`MIX LONG / RADIO FRAME “z-l-I-
`MIN SHORT RADIO FRAME m-WW
`
`n___m_fi
`
`-“
`
`n_mnnn
`
`un____
`
`nn_____n
`
`un_n_nn_
`
`nn______
`
`mn______
`
`nn______
`
`un__mn_n
`
`FIG_ 6 EXEMPLARY LONG FRAME CONFIGURATIONS vs. SUBFRAME DURATION
`
`
`
` V//////V///////,IV/~/////
`
`
`
`
`
`O.5ms
`0 5m
`0 5m
`0.5ms
`O.5ms
`0.5ms
`LONG
`
`4
`
`
`
`
`
`
`
`
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 4 0f 19
`
`US 2007/0064669 A1
`
`701701
`702M010 FRAME CONSTRUCTED FRoM SHORT FRAMES
`
`
`
`//|||||||||||I!!
`SHORTvFRAMES
`
`
`RADIO FRAME n
`
`
`
`
`
`
`
`
`
`
`RADIO FRAME n-1
`
`SYNCHRONISATION AND
`\
`CONTROL REGION /
`7
`RADIO FRAME CONSTRUCTED FROM LONG FRAMES
`\\
`
`’/
`
`RADIO FRAME (TOms)
`
`\\
`
`V L
`
`ONG FRAME
`
`E CONTROL SYMBOL
`
`FIG. 7
`
`- I RADIO FRAME n-1I RADIO FRAME n I RADIO FRAME n+1
`/_/
`\\\
`/ RADIO FRAME (10ms)
`\
`’
`RADIO FRAME CONSTRUCTED FROM LONG FRAMEs \
`
`
`
`SHORTFRAMES
`
`\LONG FRAME
`
`EGONTROL SYMBOL
`
`SHORT FRAMES
`
`I:I
`
`LONG FRAMES
`
`FIG. 8
`
`5
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 5 0f 19
`
`US 2007/0064669 A1
`
`CYCLIC
`PREFIX
`
`NORMAL SUB-FRAME
`10 OFDM SYMBOLS
`
`9“
`
`I
`
`O5ms
`
`
`"IIIIIIIIII
`FIG. 9
`50.0445
`
`PAYLOAD
`
`50.56413<—>
`44.44 s
`,
`“
`
`QQQ
`
`CYCLIC
`pREFIX
`
`BROADCAST SUB-FRAME
`
`9 OFDM SYMBOLS
`
`W
`
`
`’””’IIIIIIIII
`FIG. 10
`I- O5ms
`
`44A4 3
`
`m_00
`
`6
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 6 0f 19
`
`US 2007/0064669 A1
`
`PARAMETER
`
`SUBFRAME CONFIGURATION
`
`
`
`RADIO FRAME DURATION wlmmmmmnmmm III-I.“
`”mania-Elm“
`-W
`SUBCARRIER SPACING kHz "WI!!!
`SYMBOL DURATION DB-55.5556 '45.4545 55.5556 50.5051 46.2965 56.8182 56.0653 48.0769 55.5556 51.282147619
`USEFUL
`us
`44.44
`’44.44A44.44
`44.44 44.44 44.44
`44.44
`44.44
`44.44
`44.44 , 44.44
`44.44
`mummmmmm-mm' 6.64//
`SYMBOLS PER SUBFRAME “Minimum-“III
`TABLE 2 — EXEMPLARY SUBFRAME CONFIGURATIONS vs. THE NUMBER OF OFDM
`SYMBOLS PER SUBFRAME AND SUBFRAME DURATION.
`
`FIG. 11
`
`PARAMETER
`
`SUBFRAME CONFIGURATION
`
`
`
`_UDDIII-LIII_-IIII_-IIII_“
`RSUBFRAMES / RADIO FRAME “IE-“nun
`
`TABLE 3 — FURTHER EXEMPLARY SUBFRAME CONFIGURATIONS vs. THE NUMBER OF
`OFDM SYMBOLS PER SUBFRAME AND SUBFRAME DURATION
`
`7
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 7 0f 19
`
`US 2007/0064669 A1
`
`NORMAL SUB—FRAME
`
`\
`
`50.0w
`//
`
`LONG FRAME
`
`
`
`
`III-.- III... %%%%%%
`EXAMPLE: 1/3 RADIO FRAME ALLOCATED TO BROADCAST
`
`
`
`EXAMPLE: 2/3 RADIO FRAME ALLOCATED TO BROADCAST
`
`
`///////////////////////////////
`‘\
`EXAMPLE: ENTIRE RADIO FRAME ALLOCATED TO BROADCAST /
`
`
`
`RADIO FRAME n+1
`
`- ..
`
`RADIO FRAME n—1
`
`RADIO FRAME n
`
`BROADCAST FRAME
`
`[::]UNICAST FRAME
`
`ESYNCHRONIZATION AND CONTROL REGION
`
`FIG. 12
`
`8
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 8 0f 19
`
`US 2007/0064669 A1
`
`NORMAL SUB-FRAME
`
`/
`: g E50.0%;
`
`\
`
`//-//-//I//-/-//I/-//-//-
`
`
`
`RADIO FRAME n-1
`
`RADIO FRAME n
`
`RADIO FRAME n+1
`
`- '-
`
`% BROADCAST FRAME
`
`|:| UNICAST FRAME
`
`ESYNCHRONIZATION AND CONTROL REGION
`
`FIG. 13
`
`9
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 9 0f 19
`
`US 2007/0064669 A1
`
`RADIO FRAME CONSTRUCTED FROM SHORT At LONG FRAMES
`
`
`
`\\N\\\\\\\\\T
`
`
`
`
`\\\T\\\\\\\\\ T\\\\\\\\\\T\
`\\\T\\\\T\\\ T\\\T\\\\\\T\
`\\\\\\l\\\\\\ T\\\\\\\\\\T\
`\\\\\\\\\\\\
`\\\\\\\\\\\\\
`\\\\\\\\\\\\
`\\\\\\\\\\\T\
`\\\T\\\\\\\\\ T\\\\\\\\\\T\
`\\\T\\\\\\\\\ T\\\\\\\\\\T\
`\\\T\\N\\\\\\
`\\\\\\\\\\\\\
`
`LONG FRAME
`
`\\T\\\\T\\\\\
`\\\\\\\\\\\\\
`\\\\\\\\\\\\\
`\\\\\\\\\\\\\
`\\\\\\\\\\\\\
`\\\\\\\\\\\\\
`\\T\\\\T\\\\\
`\\\\\\\\\\\\\
`
`\\\\\\\\\\\\\
`\\\\T\\\\\\\T
`\u\\\\\\\\\\
`\\\\\\\\\\\\T
`\\\\\\\\\\\\\
`\\\\\\\\\\\\T
`\\\\\\\\\\\\T
`
`
`
`\\\T\\\\\\\\
`\\\\\\T\\\\\
`\\\T\\\\T\\\
`\\T\\\\\
`mum \l\\\\\\\\\\
`\\\\\\\\
`\\\\\\\\\\\\
`\\\\\\\\
`\\\\\\\\\\\\
`\\T\\\\\
`\\\T\\\\\\\\
`\\T\\\\\
`\\\T\\\\\\\\
`\\T\\\\\
`\\\T\\\\\\\\
`
`
`SHORT FRAMES
`
`
`
`
`
`
`
`
`
`EESHORT FRAMES
`|:|LONO FRAME
`ESYNCHRONIZATION AND CONTROL REGION
`IjSUD—FRAME
`IcELL SYNCHRONIZATION SYMBOL
`LOBAL SYNCHRONIZATION SYMBOL
`
`
`IOOMMON PILOT
`.CONTROL
`IDATA
`PCH — PAGING CHANNEL INFORMATION
`' BCCH — BROADCAST OONTROL CHANNEL INFO
`
`— PAGINC INDICATORS
`- ACKNOWLEDGEMENT INDICATORS
`
`
`
`— OTHER INDICATORS (NOT SPECIFIED)
`— BROADCAST INDICATORS
`
`FIG- 14
`
`10
`
`10
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 10 0f 19
`
`US 2007/0064669 A1
`
`V \
`
`V A
`
`VA
`
`RADIO FRAME i CONSTRUCTED FROM SHORT & LONG FRAMES
`SYNCHRONIZATION
`
`
`AND CONTROL
`
`
`
`
`0.5ms
`0.5ms
`0.5ms
`‘V
`REGION (EVERY
`
`
`
`
`
`m”
`jth RADIO FRAME)
`\\\\\A
`In
`EDDDDRDDD
`DRDRDDRDD
`RA
`mIII/A
`VII/l
`
`
`\\\\\\
`\\\\\\
`
`
`
`
`\\I\\\H\\\\\
`\\\\\\\\\\\\\
`\\\\\\\\\\\\
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`\\\\I\\\\\\\\
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`\\\\\\\\\\\\\
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`\A\\\\\\\
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`\\\\\\\I\\\\I
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`\I\\\\\\\
`\\\H\\\\\\\\
`\H\\\\\\\\\\
`\\I\\\H\\\\\
`\\\\\\\H\\\
`\I\\\\\H\\\
`\\\\\\\I\\\H
`\\\\\\\\\I\\\
`
`
`
`
`
`\\I\\\H\\\\\
`\A\\\\\\\
`\\\\\\\\I\\\
`\\\\\\\H\\\
`\\\\I\\\\\\\\
`\\\\\\\\\\\\\
`\\\\\\\I\\\\I
`\\\\\\\\\\\\\
`\\I\\L\I\\\L\
`\\\\L\\\\
`\\\\L\\\I\\\
`\\\\\\\\\\\\
`\\L\\\\\\\\\\
`\L\\\\\\\\\\\
`\\\\\\\\\\L\I
`\L\\\\\L\\\\\
`\\\\\\\\\
`\m\m\\\u u\\\\\\\\\\\
`\\\\\\\m\\
`\\\\\\\\T\\\
`\\m\\\\\\\\
`\\\\\\\m\\\ \\\\\\\\\\\\A
`\\\\L\\\\
`\manm \L\\\\\\\\\\\
`\\\\\\\u\\\
`\\\\\\m\\\
`\\m\\\\\\\\
`\\\\\\\m\\\ \\\\\\\\\\m
`
`\\\\\\\L\\\\
`\\\\\\\\\m
`muumu \\L\\\\\\\\\\
`mummu \L\\\\\\\\\\\
`\\\\\\\L\\\\\
`\\\\\\\\\\L\\
`‘
`
`
` RADIO FRAME i+1
`
`u.
`
`
`
`DL
`
`
`
`LONG FRAME
`
`
`
`
`
`
`
`
`
`
`
`mSHORT FRAMES ESYNCHRONIZATION AND CONTROL REGION
`ljsua—TRANE
`I:ILONG FRAME
`ICELL SYNCHRONIZATION SYMBOL
`LOBAL SYNCHRONIZATION SYMBOL
`
`ONNON PILOT
`
`ICONTROL
`IDATA
`.PCH - PAGING CHANNEL INFORMATION
`BCCH — BROADCAST CONTROL CHANNEL INFO
`
`||]]]]]]PI — PAGING INDICATORS
`IAI - ACKNONLEDCENENT INDICATORS
`mm — OTHER INDICATORS (NOT SPECIFIED)
`BI — BROADCAST INDICATORS
`
`
`11
`
`11
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 11 0f 19
`
`US 2007/0064669 A1
`
`---
`
`SUPER FRAME i—1
`
`SUPER FRAME i
`
`RADIO FRAME:
`SYNCHRONIZATION AND
`SUPER FRAME i+1
`\ CONTROL REGION
`\\\\
`RADIO FRAME n é%§_
`'1 l .‘E
`‘—’
`
`RADIO FRAME n—1
`
`RADIO FRAME D H.
`
`
`
`/
`
`RADIO FRAME 0
`
`no
`
`/
`
`RADIO FRAME (lOms)
`
`\\
`
`/
`
`RADIO FRAME CONSTRUCTED FROM SHORT AND LONG FRAMES \
`
`
`
`
`SHORTFRAMES
`
`LONG FRAME
`
`FIG- 16
`
`MSHORF FRAMES
`|:|LoMc FRAME
`ESYMCHRoNIZAFIoM AND CONTROL REGION
`DSUB-FRAME
`
` V SUPER FRAME CONTROL REGION
`
`SUPER FRAME k
`
`12
`
`SUPER FRAME'
`CONTROL REGION
`
`12
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 12 0f 19
`
`US 2007/0064669 A1
`
`SUPER FRAME i—1
`’
`
`SUPER FRAME i
`
`
`
`RADIO FRAME n
`4—»
`
`RADIO FRAME:
`SYNCHRONIZAHON AND
`SUPER FRAME i+1
`‘\ CONTROL REGION
`
`\\ \ \
`3331:
`RADIO FRAME O
`
`
`63/3355
`
`
`SUPER FRAME'
`CONTROL REGION
`
`//
`
`RADIO FRAME (10ms)
`
`\\
`
`\
`/
`
`RADIO FRAME CONSTRUCTED FROM SHORT AND LONG FRAMES \
`
`
`
`\m
`
`\ \
`
`\\\\
`
`SHORT FRAMES
`
`LONG FRAME
`
`FIG. 1 7
`
`mSHORT FRAMES
`|:|LOMO FRAME
`ESYMOHRONHAFIOM AND CONTROL REGION
`ljSUB—FRAME
`33E SUPER FRAME CONTROL REGION
`SUPER FRAME k
`
`
`13
`
`13
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 13 0f 19
`
`US 2007/0064669 A1
`
`SYNCHRONIZATION
`AND CONTROL
`REGION
`
`,
`RADIO FRAME CONSTRUCTED FROM SHORT & LONG FRAMES
`
`
`_, .—/
`
`
`
`
`
`
`
`\A\\\\\\\\\\
`\\\\m\\\\\\
`\A\\\\\\\\\\\ \\\\m\\\\\\
`
`\\\\\\\\\\\\\ \\\\\\\\\\\\\
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`\\\\\\\\\\\\\ \\\\\\M\\\\\
`\A\\\\\\\\\\\ \\\\\\m\\\\
`\\\\\\\\\\\\\ \\\\\\m\\\\
`\A\\\\\\\\\\\ \\\\\\\\\\\\\
`\ \
`
`‘\
`
`DL
`
`UL
`
`FRAME
`OFFSET
`
`RACH
`
`LONG FRAME
`\\\\\\\\\\\\\
`\\\\\\\\\\\\\
`\\\\\\\\\\\\A \\\\\\\\\\\\\
`\\\\\\\\\\\\\
`\\\\\\\\\\\\\
`
`\\\\\\\\\\\\\
`\\\\\\\\\\\\\
`\\\\\\\\\\\\\
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`\\\\\\\\\\\\\
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`/
`
`/
`
`\
`\
`
`/
`
`\\\\\\\\\\u\ mmmuu
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`\
`
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`
`\\\\\\\\\\\\\ \\\\\\\\\\\\\
`\n\\\\\\\\\\
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`\\\\\\\\\\\\\ \A\\\\\\\\\\\
`\m\\\\\\\\\
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`
`\\\\\\\\\\A\V \\\\\\\\\\\\\
`\A\\\\\\\\\\\
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`
`
`
`
`ARMZRMAAMAEZA AAARAAR
`O5ms
`O5ms
`O ms
`
`ONE DOWNLINK AND UPLINK RADIO FRAME STRUCTURE
`
`FIG- 18
`
`.RACH
`mSHORT FRAMES
`IcoMMoM PILOT
`|:|LoMc FRAME
`ESYMCHROMIZAFIOM AND CONTROL REGION .CONTROL
`DSUB—FRAME
`DATA
`3:: SUPER FRAME CONTROL REGION
`SUPER FRAME k
`
`14
`
`14
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 14 0f 19
`
`US 2007/0064669 A1
`
`/
`
`
`P
`RADIO FRAME CONSTRUCTED FROM SHORT & LONG FRAMES
`,
`
`SYNCHRONIZATION
`
`
`
`
`
`AND CONTROL m
`0.5ms
`O.5ms
`
`
`
`/
`/
`/
`“Em"
`”‘
`ROEVmRMgfifiyfifigfigggéfimgfiggfifi
`L
`
`
`
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`
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`
`
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`
`
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`
`
`DL
`
`LONG FRAME
`
`
`
`
`
`
`
`FRAME
`”
`
`OFFSET
`LONG RACH LONG FRAME / OATAT
`EVERY 100ms OTHERWISE
`OATA LONG FRAME
`
`I
`
`\\
`OATAT\
`
`CONTROL
`
`
`
`SHORT RACH
`
`SUBFRAME
`
`ALTERNATIVE UPLINK FRAME STRUCTURE
`
`IRAcH
`mSHORT FRAMES
`.COMMON PILOT
`|:|LOMO FRAME
`ESYMOHROMIIATIOM AND CONTROL REOION .CONTROL
`ljsua-FRAME
`.DATA
` ' SUPER FRAME CONTROL REGION
`
`SUPER FRAME k
`
`FIG. 19
`
`15
`
`15
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 15 0f 19
`
`US 2007/0064669 A1
`
`
`RADIO FRAME CONSTRUCTED FROM SHORT & LONG FRAMES
`1
`l‘
`
`SYNCHRONIZATION
`
`AND CONTROL
`.
`0.5ms
`O.5ms
`
`
`
`
`REGION
`3::
`7
`7
`7
`,
`/
`/
`/
`
`RWRRRRO§R7R§§§§RRRR7RRRRRR RR/ -
`
`
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`
`\\\\\\\\\\\\
`\\\\\\\\\\\\
`
`
`LONG FRAME
`
`
`,
`
`\
`
`,
`
`,
`
`DL
`
`FRAME
`OFFSET LONG RAOH LONc FRAME
`EVERY lOOms OTHERWISE
`DATA LONG FRAME
`
`
`
`\‘\
`
`'
`
`ALTERNATIVE UPLINK FRAME STRUCTURE
`
`SHORT RACH
`
`SHORT RACH
`SUBFRAME
`
`RACH GUARD
`
`mSHORT FRAMES
`IRAOH
`I:|LONG FRAME
`'
`OMMON PILOT
`
`ESYNOHRONIIATION AND CONTROL REGION .CONTROL
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`
`Patent Application Publication Mar. 22, 2007 Sheet 16 0f 19
`
`US 2007/0064669 A1
`
`SYNCHRONIZATION
`AND CONTROL
`REGION
`
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`
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`
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`
`17
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 17 0f 19
`
`US 2007/0064669 A1
`
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`19
`
`
`
`Patent Application Publication Mar. 22, 2007 Sheet 19 0f 19
`
`US 2007/0064669 A1
`
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`
`20
`
`20
`
`
`
`
`US 2007/0064669 A1
`
`Mar. 22, 2007
`
`METHOD AND APPARATUS FOR REDUCING
`ROUND TRIP LATENCY AND OVERHEAD
`WITHIN A COMMUNICATION SYSTEM
`
`RELATED APPLICATIONS
`
`[0001] This application claims priority to US. Provisional
`Application Ser. No. 60/666,494 filed Mar. 30, 2005.
`
`FIELD OF THE INVENTION
`
`[0002] The present invention relates generally to commu-
`nication systems and in particular, to a method and apparatus
`for reducing round-trip latency and overhead within a com-
`munication system.
`
`BACKGROUND OF THE INVENTION
`
`[0003] One of the key requirements for wireless broad-
`band system development, such as in the 3rd generation
`partnership project (3GPP) Long Term Evolution (LTE), is
`reducing latency in order to improve user experience. From
`a link layer perspective,
`the key contributing factor to
`latency is the round-trip delay between a packet transmis-
`sion and an acknowledgment of the packet reception. The
`round-trip delay is typically defined as a number of frames,
`where a frame is the time duration upon which scheduling is
`performed. The round-trip delay itself determines the overall
`automatic repeat request (ARQ) design, including design
`parameters such as the delay between a first and subsequent
`transmission of packets, or the number of hybrid ARQ
`channels (instances). A reduction in latency with the focus
`on defining the optimum frame duration is therefore key in
`developing improved user experience in future communica-
`tion systems. Such systems include enhanced Evolved Uni-
`versal Terrestrial Radio Access (UTRA) and Evolved Uni-
`versal Terrestrial Radio Access Network (UTRAN) (also
`known as EUTRA and EUTRAN) within 3GPP, and evolu-
`tions of communication systems within other technical
`specification generating organizations (such ‘Phase 2’ within
`3GPP2, and evolutions of IEEE 802.11, 802.16, 802.20, and
`802.22).
`
`[0004] Unfortunately, no single frame duration is best for
`different traffic types requiring different quality of service
`(QoS) characteristics or offering differing packet sizes. This
`is especially true when the control channel and pilot over-
`head in a frame is considered. For example, if the absolute
`control channel overhead is constant per user per resource
`allocation and a single user is allocated per frame, a frame
`duration of 0.5 ms would be roughly four times less efficient
`than a frame duration of 2 ms. In addition, different frame
`durations could be preferred by different manufacturers or
`operators, making the development of an industry standard
`or compatible equipment difficult. Therefore, there is a need
`for an improved method for reducing both round-trip latency
`and overhead within a communication system.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0005] FIG. 1 is a block diagram of a communication
`system.
`
`[0006] FIG. 2 is a block diagram of circuitry used to
`perform uplink and downlink transmission.
`
`[0007] FIG. 3 is a block diagram of a radio frame.
`
`[0008]
`frames.
`
`[0009]
`frames.
`
`FIG. 4 shows a sequence of consecutive short
`
`FIG. 5 shows a sequence of consecutive long
`
`FIG. 6 shows a table for a 10 ms radio frame and
`[0010]
`subframes of approximately 0.5 ms, 0.55556 ms, 0.625 ms,
`and 0.67 ms.
`
`FIG. 7 shows examples for the third data column of
`[0011]
`Table 1, with 0.5 ms subframes and 6 subframes per long
`frame (3 ms).
`
`FIG. 8 shows two examples of radio frames based
`[0012]
`on a combination of 2 ms long frames and 0.5 ms short
`frames.
`
`FIG. 9 shows a subframe comprised ofj=10 OFDM
`[0013]
`symbols each with a cyclic prefix 901 of 5.56 us which may
`be used for unicast transmission.
`
`FIG. 10 shows a ‘broadcast’ subframe comprised
`[0014]
`ofj=9 symbols each with a cyclic prefix 1001 of 11.11 us
`which may be used for broadcast transmission.
`
`FIG. 11 shows a table having examples of three
`[0015]
`subframe types.
`
`FIG. 12 shows a long frame composed entirely of
`[0016]
`broadcast subframes or composed entirely of normal (uni-
`cast) subframes.
`
`FIG. 13 shows a short frame composed of either a
`[0017]
`normal or a broadcast subframe and one or more broadcast
`
`type short frames.
`
`FIG. 14 shows an example of the radio frame
`[0018]
`overhead.
`
`FIG. 15 shows an alternate Radio Frame structure
`[0019]
`of arbitrary size where the synchronization and control
`(S+C) region is not part of a radio frame but part of a larger
`hierarchical
`frame structure composed of radio frames
`where the (S+C) region is sent with every j Radio Frames.
`
`FIG. 16 and FIG. 17 illustrate a hierarchical frame
`[0020]
`structure where a Super frame is defined to be composed of
`n+1 radio frames.
`
`FIG. 18 shows the uplink subframes to be of the
`[0021]
`same configuration as the downlink subframes.
`
`FIG. 19 through FIG. 21 show 2 ms long frames
`[0022]
`composed of 0.5 ms subframes that are of frame type long
`RACH, Data, or Composite.
`
`FIG. 22 through FIG. 24 show short frame fre-
`[0023]
`quency selective (FS) and frequency diverse (FD) resource
`allocations respectively for several users.
`
`DETAILED DESCRIPTION OF THE DRAWINGS
`
`In order to address the above-mentioned need, a
`[0024]
`method and apparatus for reducing round-trip latency is
`provided herein. During operation radio frames are divided
`into a plurality of subframes. Data is transmitted over the
`radio frames within a plurality of subframes, and having a
`frame duration selected from two or more possible frame
`durations.
`
`[0025] The present invention encompasses a method for
`reducing round-trip latency within a communication system.
`
`21
`
`21
`
`
`
`US 2007/0064669 A1
`
`Mar. 22, 2007
`
`The method comprises the steps of receiving data to be
`transmitted over a radio frame, where the radio frame is
`comprised of a plurality of subframes. A frame duration is
`selected from two or more possible frame durations, where
`a frame is substantially equal to a multiple of subframes. The
`data is placed within the multiple subframes to produce
`multiple subframes of data, and the frame is transmitted
`having the multiple subframes of data over the radio frame.
`
`invention additionally comprises a
`[0026] The present
`method comprising the steps of receiving data to be trans-
`mitted to a first user over a radio frame, where the radio
`frame is comprised of a plurality of subframes. A frame
`duration is selected for the first user from two or more
`
`possible frame durations, where a frame is substantially
`equal to a multiple of subframes. The data for the first user
`is placed within the multiple subframes to produce multiple
`subframes of data and then transmitted to the first user
`
`having the multiple subframes of data over the radio frame.
`Second data is received to be transmitted to a second user
`over the radio frame. A second frame duration is selected for
`
`the second user from the two or more possible frame
`durations, where a second frame is substantially equal to
`multiple of subframes. The second data for the second user
`is placed within the multiple subframes to produce second
`multiple subframes of data, and the second frame is trans-
`mitted to the second user having the second multiple sub-
`frames of data over the radio frame.
`
`[0027] The present invention encompasses a method for
`transmitting data within a communication system. The
`method comprises the steps of receiving data to be trans-
`mitted over a radio frame, where the radio frame is com-
`prised of a plurality of subframes. A frame length is selected
`comprising multiple subframes and a subframe type is
`selected from one of two or more types of subframes for the
`multiple of subframes. The data is placed within the multiple
`subframes to produce multiple subframes of data and the
`frame is transmitted having the multiple subframes of data
`and the subframe type over the radio frame.
`
`[0028] The present invention encompasses a method for
`transmitting data within a communication system. The
`method comprises the steps of receiving data to be trans-
`mitted over a radio frame, where the radio frame is com-
`prised of a plurality of subframes. A frame is selected
`wherein the frame is substantially equal to a multiple of
`subframes. The data is placed within the multiple subframes
`to produce multiple subframes of data and a common pilot
`is placed within each subframe of the multiple subframes.
`The frame having the multiple subframes of data is trans-
`mitted over the radio frame.
`
`[0029] The present invention encompasses a method for
`transmitting data within a communication system. The
`method comprises the steps of determining a system band-
`width from two or more system bandwidths and receiving
`data to be transmitted over a radio frame and the system
`bandwidth. The radio frame is comprised of a plurality of
`subframes, and a radio frame duration and a subframe
`duration is based on the system bandwidth. A frame is
`selected, where a frame is substantially equal to a multiple
`of subframes. The data is placed within the multiple sub-
`frames to produce multiple subframes of data and the frame
`is transmitted having the multiple subframes of data and the
`subframe type over the radio frame.
`
`[0030] A method for transmitting data within a commu-
`nication system. The method comprises the steps of deter-
`mining a carrier bandwidth and receiving data to be trans-
`mitted over a radio frame, where the radio frame is
`comprised of a plurality of subframes. A frame is selected,
`where the frame is substantially equal
`to a multiple of
`subframes and each subframe is comprised of resource
`elements, where a resource element comprises multiples of
`sub-carriers such that a carrier bandwidth is divided into a
`
`number of resource elements. The data is placed within the
`multiple subframes to produce multiple subframes of data
`and the frame is transmitted having the multiple subframes
`of data and the subframe type over the radio frame.
`
`[0031] Turning now to the drawings, wherein like numer-
`als designate like components, FIG. 1 is a block diagram of
`communication system 100. Communication system 100
`comprises a plurality of cells 105 (only one shown) each
`having a base transceiver station (BTS, or base station) 104
`in communication with a plurality of remote, or mobile units
`101-103. In the preferred embodiment of the present inven-
`tion, communication system 100 utilizes a next generation
`Orthogonal Frequency Division Multiplexed (OFDM) or
`multicarrier based architecture, such as OFDM with or
`without cyclic prefix or guard interval (e.g., conventional
`OFDM with cyclic prefix or guard interval, OFDM with
`pulse shaping and no cyclic prefix or guard interval (OFDM/
`OQAM with IOTA (Isotropic Orthogonal Transform Algo-
`rithm) prototype filter), or single carrier with or without
`cyclic prefix or guard interval (e.g., IFDMA, DFT—Spread-
`OFDM), or other. The data transmission may be a downlink
`transmission or an uplink transmission. The transmission
`scheme may include Adaptive Modulation and Coding
`(AMC). The architecture may also include the use of spread-
`ing techniques such as multi-carrier CDMA (MC-CDMA),
`multi-carrier direct sequence CDMA (MC-DS-CDMA),
`Orthogonal Frequency and Code Division Multiplexing
`(OFCDM) with one or two dimensional spreading, or may
`be based on simpler time and/or frequency division multi-
`plexing/multiple access techniques, or a combination of
`these various techniques. However,
`in alternate embodi-
`ments communication system 100 may utilize other wide-
`band cellular communication system protocols such as, but
`not limited to, TDMA or direct sequence CDMA.
`
`In addition to OFDM, communication system 100
`[0032]
`utilizes Adaptive Modulation and Coding (AMC). With
`AMC, the modulation and coding format of a transmitted
`data stream for a particular receiver is changed to predomi-
`nantly match a current received signal quality (at
`the
`receiver) for the particular frame being transmitted. The
`modulation and coding scheme may change on a frame-by-
`frame basis in order to track the channel quality variations
`that occur in mobile communication systems. Thus, streams
`with high quality are typically assigned higher order modu-
`lations rates and/or higher channel coding rates with the
`modulation order and/or the code rate decreasing as quality
`decreases. For those receivers experiencing high quality,
`modulation schemes such as 16 QAM, 64 QAM or 256
`QAM are utilized, while for those experiencing low quality,
`modulation schemes such as BPSK or QPSK are utilized.
`
`[0033] Multiple coding rates may be available for each
`modulation scheme to provide finer AMC granularity,
`to
`enable a closer match between the quality and the transmit-
`ted signal characteristics (e.g., R=%, 1/z, and 3A for QPSK;
`
`22
`
`22
`
`
`
`US 2007/0064669 A1
`
`Mar. 22, 2007
`
`R=1/2 and R=2/3 for 16 QAM, etc.). Note that AMC can be
`performed in the time dimension (e.g., updating the modu-
`lation/coding every Nt OFDM symbol periods) or in the
`frequency dimension (e.g., updating the modulation/coding
`every NSC subcarriers) or a combination of both.
`
`[0034] The selected modulation and coding may only
`predominantly match the current received signal quality for
`reasons such as channel quality measurement delay or errors
`or channel quality reporting delay. Such latency is typically
`caused by the round-trip delay between a packet transmis-
`sion and an acknowledgment of the packet reception.
`
`In order to reduce latency, a Radio Frame (RAF)
`[0035]
`and subframe are defined such that the RAF is divided into
`
`a number (an integer number in the preferred embodiment)
`of subframes. Within a radio frame, frames are constructed
`from an integer number of subframes for data transmission,
`with two or more frame durations available (e.g., a first
`frame duration of one subframe, and a second frame dura-
`tion of three subframes).
`
`[0036] For example, a 1 0 ms core radio frame structure
`from UTRA may be defined, with Nrf subframes per radio
`frame (e.g., Nfl=20 Tsf=0.5 ms subframes, where Tsf=dura-
`tion of one subframe). For OFDM transmission, subframes
`comprise an integer number P of OFDM symbol intervals
`(e.g., P=10 for Tsn=50 us symbols, where Tsn=duration of
`one OFDM symbol), and one or more subframe types may
`be defined based on guard interval or cyclic prefix (e.g.,
`normal or broadcast).
`
`[0037] As one of ordinary skill in the art will recognize, a
`frame is associated with a scheduled data transmission. A
`
`frame may be defined as a resource that is ‘schedulable’, or
`a schedulable unit,
`in that
`it has an associated control
`structureipossibly uniquely associatedithat controls the
`usage of the resource (i.e. allocation to users etc.). For
`example, when a user is to be scheduled on a frame, a
`resource allocation message corresponding to a frame will
`provide resources (e.g., for an OFDM system a number of
`modulation symbols each of one subcarrier on one OFDM
`symbol) in the frame for transmission. Acknowledgements
`of data transmissions on a frame will be returned, and new
`data or a retransmission of data may be scheduled in a future
`frame. Because not all resources in a frame may be allocated
`in a resource allocation (such as in an OFDM system), the
`resource allocation may not span the entire available band-
`width and/or time resources in a frame.
`
`[0038] The different frame durations may be used to
`reduce latency and overhead based on the type of traffic
`served. For example, if a first transmission and a retrans-
`mission are required to reliably receive a voice over internet
`protocol (VoIP) data packet, and a retransmission can only
`occur after a one frame delay, allocating resources within a
`0.5 ms frame instead of a 2 ms frame reduces latency for
`reliable reception from 6 ms (transmission,
`idle frame,
`retransmission) to 1.5 ms. In another example, providing a
`resource allocation that will fit a user’s packet without
`fragmentation, such as a 1 ms frame instead of a 0.5 ms
`frame, can reduce overhead such as control and acknowl-
`edgement signaling for multiple fragments of a packet.
`
`aggregation of
`the
`reflecting
`names
`[0039] Other
`resources such as consecutive OFDM symbols may be used
`instead of subframe, frame, and radio frame. For example,
`
`the term ‘slot’ may be used for ‘subframe’, or ‘transmission
`time interval (TTI)’ used for ‘frame’ or ‘frame duration’. In
`addition, a frame may be considered a user transmission
`specific quantity (such as a TTI associated with a user and
`a data flow), and frames therefore need not be synchronized
`or aligned between users or even transmissions from the
`same user (e.g., one subframe could contain parts of two
`data transmissions from a user, the first transmitted in a one
`subframe frame and the second transmitted in a four sub-
`
`frame frame). Of course, it may be advantageous to restrict
`either transmissions with a user or transmissions with mul-
`
`tiple users to have synchronized or aligned frames, such as
`when time is divided into a sequence of 0.5 ms or 2 ms
`frames and all resource allocations must be within these
`
`frames. As indicated above a radio frame can represent an
`aggregation of subframes or frames of different sizes or an
`aggregation of resources such as consecutive OFDM or
`DFT—SOFDM symbols exceeding the number of such sym-
`bols in a subframe where each symbol is composed of some
`number of subcarriers depending on the carrier bandwidth.
`
`[0040] The radio frame structure may additionally be used
`to define common control channels for downlink (DL)
`transmissions (such as broadcast channels, paging channels,
`synchronization channels, and/or indication channels) in a
`manner which is time-division multiplexed into the sub-
`frame sequence, which may simplify processing or increase
`battery life at the user equipment (remote unit). Similarly for
`uplink (UL) transmissions, the radio frame structure may
`additionally be used to define contention channels (e.g.
`random access channel_(RACH)), control channels includ-
`ing pilot time multiplexed with the shared data channel.
`
`FIG. 2 is a block diagram of circuitry 200 for base
`[0041]
`station 104 or mobile station 101-103 to perform uplink and
`downlink transmission. As shown, circuitry 200 comprises
`logic circuitry 201,
`transmit circuitry 202, and receive
`circuitry 203. Logic circuitry 200 preferably comprises a
`microprocessor controller, such as, but not
`l