(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2010/0093386 A1
`(43) Pub. Date:
`Apr. 15, 2010
`Damnjanovic et al.
`
`US 20100093386A1
`
`(54) RANDOM ACCESS FOR WIRELESS
`COMMUNICATION
`
`(75) Inventors:
`
`Aleksandar Damnj anovic, Del
`Mar, CA (US); Durga Prasad
`Malladi, San Diego, CA (US);
`Juan Montoj 0, San Diego, CA
`(Us)
`
`Correspondence Address:
`QUALCOMM INCORPORATED
`5775 MOREHOUSE DR.
`SAN DIEGO, CA 92121 (US)
`
`(73) Assignee:
`
`QUALCOMM
`INCORPORATED, San Diego,
`CA (US)
`
`(21) Appl. No.:
`
`12/443,783
`
`(22) PCT Filed:
`
`Oct. 31, 2007
`
`(86) PCT No.:
`
`PCT/US07/83239
`
`§ 371 (0X1)’
`(2), (4) Date:
`
`Jul. 2, 2009
`
`Related US. Application Data
`
`(60) Provisional application No. 60/855,903, ?led on Oct.
`31, 2006.
`Publication Classi?cation
`
`(51) Int. Cl.
`(2006.01)
`H04B 7/005
`(52) U.S. Cl. ...................................................... .. 455/522
`(57)
`ABSTRACT
`
`Techniques for sending messages for system access are
`described. In one aspect, a user equipment (UE) sends a ?rst
`message With poWer headroom and/ or buffer siZe information
`for system access. A Node B determines at least one param
`eter (e.g., a resource grant, poWer control information, etc.)
`based on the poWer headroom and/or buffer siZe information.
`The Node B sends a second message With the parameter(s).
`The UE sends a third message based on the parameter(s), e. g.,
`With uplink resources indicated by the resource grant, With
`transmit poWer determined based on the poWer control infor
`mation, etc. In another aspect, the UE sends a radio environ
`ment report in the third message. The report may be used to
`select a cell and/or a frequency for the UE. In yet another
`aspect, the second message includes poWer control informa
`tion, and the UE sends the third message based on the poWer
`control information.
`
`(
`
`Start
`i
`
`D 1600
`,1612 ‘J
`
`Receive a first message sent
`by a UE for system access
`i
`,1614
`Determine power control information
`based on the first message
`i
`{1616
`Send a second message comprising
`the power control information to the UE
`i
`[1618
`Receive a third message sent by the
`UE with transmit power determined
`based on the power control information
`i
`End
`
`C
`
`Page 1 of 20
`
`LG Electronics Exhibit 1005
`
`

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`Patent Application Publication
`
`Apr. 15, 2010 Sheet 1 0f 10
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`US 2010/0093386 A1
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`Patent Application Publication
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`Apr. 15, 2010 Sheet 6 0f 10
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`600
`r-/
`
`(
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`r614
`
`)
`Start
`,612
`i
`Send a first message comprising
`power headroom information
`for system access by a UE
`l
`Receive a second message
`comprising at least one parameter
`determined based on the power
`headroom information
`,616
`i
`Send a third message based
`on the at least one parameter
`l
`End
`
`C
`
`)
`
`FIG. 6
`
`700
`K“
`,712
`Module to send a first message
`comprising power headroom
`information for system access by a UE
`r714
`
`Module to receive a second
`message comprising at least one
`parameter determined based on
`the power headroom information
`,716
`Module to send a third message
`based on the at least one parameter
`
`FIG. 7
`
`Page 7 of 20
`
`

`
`Patent Application Publication
`
`Apr. 15, 2010 Sheet 7 0f 10
`
`US 2010/0093386 A1
`
`C
`
`Start
`
`800
`r/
`
`D
`
`1812
`$
`Receive a first message comprising
`power headroom information
`sent by a UE for system access
`i
`{814
`Determine at least one
`parameter based on the
`power headroom information
`i
`Send a second message
`comprising the at least
`one parameter to the UE
`l
`Receive a third message
`sent by the UE based on
`the at least one parameter
`l
`End
`
`,816
`
`r818
`
`FIG. 8
`
`900
`rd
`
`[912
`
`Module to receive a first
`message comprising power
`headroom information sent
`by a UE for system access
`
`Module to determine at least
`one parameter based on the
`power headroom information
`
`,914
`
`,916
`
`Module to send a second
`message comprising the at
`least one parameter to the UE
`,918
`
`Module to receive a third
`message sent by the UE based
`on the at least one parameter
`
`FIG. 9
`
`Page 8 of 20
`
`

`
`Patent Application Publication
`
`Apr. 15, 2010 Sheet 8 0f 10
`
`US 2010/0093386 A1
`
`1000
`V
`
`C
`
`D
`,1012
`
`Start
`l,
`Perform a random access
`procedure for system access by a UE
`i
`{1014
`Send a random access preamble
`l
`[1016
`.
`Receive a random access response
`
`11018
`$
`Send a message comprising a
`radio environment report during
`the random access procedure
`
`Q
`
`‘
`End
`FIG. 10
`
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`
`1100
`x“
`,1112
`Module to perform a random access
`procedure for system access by a UE
`l
`,1114
`Module to send a
`random access preamble
`
`,1116
`
`l
`Module to receive a
`random access response
`+
`
`1118
`1'
`Module to send a message comprising
`a radio environment report during
`the random access procedure
`
`FIG. 11
`
`Page 9 of 20
`
`

`
`Patent Application Publication
`
`Apr. 15, 2010 Sheet 9 0f 10
`
`US 2010/0093386 A1
`
`1200
`r/
`
`C
`
`)
`Start
`,1212
`l
`Receive a random access preamble
`sent by a UE for system access
`l
`[1214
`Send a random access response
`
`{7215
`$
`Receive a message comprising a
`radio environment report from the UE
`
`‘
`Determine a cell and/or a
`frequency for the UE based on
`the radio environment report
`
`r7218
`
`‘
`Direct the UE to the
`selected cell and/or frequency
`
`r1220
`
`1300
`5*’
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`Module to receive a random
`access preamble sent by
`a UE for system access
`|
`Module to send a
`random access response
`I
`
`1316
`/
`Module to receive a message
`comprising a radio environment
`report from the UE
`
`,1314
`
`1318
`I
`Module to determine a cell and/
`or a frequency for the UE based
`on the radio environment report
`[1320
`
`C
`
`‘
`End
`
`FIG. 12
`
`)
`
`Module to direct the UE to the
`selected cell and/or frequency
`
`FIG- 13
`
`Page 10 of 20
`
`

`
`Patent Application Publication
`
`Apr. 15, 2010 Sheet 10 0f 10
`
`US 2010/0093386 A1
`
`) 1400
`,1412
`
`C
`
`Start
`i
`Send a first message
`for system access by a UE
`i
`,1414
`Receive a second message
`comprising power control information
`i
`[1416
`Send a third message with
`transmit power determined based
`on the power control information
`
`1500
`r“
`,1512
`Module to send a first message
`for system access by a UE
`|
`,1514
`Module to receive a second message
`comprising power control information
`|
`[1516
`Module to send a third message with
`transmit power determined based
`on the power control information
`
`C
`
`End
`
`FIG. 14
`
`)
`
`FIG. 15
`
`(
`
`D 1600
`Start
`,1612 r’
`i
`Receive a first message sent
`by a UE for system access
`r1614
`l
`Determine power control information
`based on the first message
`i
`[1616
`Send a second message comprising
`the power control information to the UE
`l
`[1618
`Receive a third message sent by the
`UE with transmit power determined
`based on the power control information
`
`Q
`
`1
`
`End
`FIG. 16
`
`)
`
`1700
`K"
`,1712
`Module to receive a first message
`sent by a UE for system access
`|
`,1714
`Module to determine power control
`information based on the first message
`|
`,1716
`Module to send a second
`message comprising the power
`control information to the UE
`
`{1718
`
`Module to receive a third
`message sent by the UE with
`transmit power determined based
`on the power control information
`
`FIG. 17
`
`Page 11 of 20
`
`

`
`US 2010/0093386 A1
`
`Apr. 15,2010
`
`RANDOM ACCESS FOR WIRELESS
`COMMUNICATION
`
`[0001] The present application claims priority to provi
`sional US. application Ser. No. 60/855,903, entitled “RAN
`DOM ACCESS FOR WIRELESS COMMUNICATION,”
`?led Oct. 31, 2006, assigned to the assignee hereof and incor
`porated herein by reference.
`
`BACKGROUND
`
`[0002] I. Field
`[0003] The present disclosure relates generally to commu
`nication, and more speci?cally to techniques for accessing a
`Wireless communication system.
`[0004] II. Background
`[0005] Wireless communication systems are Widely
`deployed to provide various communication content such as
`voice, video, packet data, messaging, broadcast, etc. These
`Wireless systems may be multiple-access systems capable of
`supporting multiple users by sharing the available system
`resources. Examples of such multiple-access systems include
`Code Division Multiple Access (CDMA) systems, Time
`Division MultipleAccess (TDMA) systems, Frequency Divi
`sion Multiple Access (FDMA) systems, Orthogonal FDMA
`(OFDMA) systems, and Single-Carrier FDMA (SC-FDMA)
`systems.
`[0006] A Wireless communication system may include any
`number of Node Bs that can support communication for any
`number of user equipments (U Es). A UE may communicate
`With a Node B via transmissions on the doWnlink and uplink.
`The doWnlink (or forWard link) refers to the communication
`link from the Node B to the UE, and the uplink (or reverse
`link) refers to the communication link from the UE to the
`Node B.
`[0007] A UE may transmit a random access preamble (or an
`access probe) on the uplink When the UE desires to gain
`access to the system. A Node B may receive the random
`access preamble and respond With a random access response
`(or an access grant) that may contain pertinent information
`for the UE. The UE and Node B may exchange additional
`messages to complete the system access for the UE. Uplink
`resources are consumed to transmit messages on the uplink,
`and doWnlink resources are consumed to transmit messages
`on the doWnlink for the system access. There is therefore a
`need in the art for techniques to e?iciently send messages for
`system access.
`
`SUMMARY
`
`[0008] Techniques for sending messages for system access
`are described herein. In one aspect, a UE may send a ?rst
`message (e.g., a random access preamble) comprising poWer
`headroom information and/or buffer siZe information for sys
`tem access. A Node B may determine at least one parameter
`(e. g., a resource grant, poWer control information, etc.) based
`on the poWer headroom and/ or buffer siZe information. The
`Node B may return a second message (e. g., a random access
`response) comprising the at least one parameter. The UE may
`then send a third message based on the at least one parameter.
`For example, the UE may send the third message With uplink
`resources indicated by the resource grant, With transmit
`poWer determined based on the poWer control information,
`etc.
`
`[0009] In another aspect, the UE may send a radio environ
`ment report in the third message. This report may include
`pilot measurements for multiple cells, multiple frequencies,
`and/or multiple systems. The report may be used to select a
`frequency and/ or a cell for the UE.
`[0010] In yet another aspect, the UE may receive poWer
`control information in the second message and may send the
`third message With transmit poWer determined based on the
`poWer control information. The Node B may determine the
`poWer control information based on received signal quality of
`the ?rst message, poWer headroom information sent in the
`?rst message, etc. The UE may determine the transmit poWer
`for the third message based on the poWer control information
`received in the second message and the transmit poWer used
`for the ?rst message.
`[0011] Various aspects and features of the disclosure are
`described in further detail beloW.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0012] FIG. 1 shoWs a Wireless multiple-access communi
`cation system.
`[0013] FIG. 2 shoWs a block diagram ofa Node B and a UE.
`[0014] FIG. 3 shoWs an initial access procedure.
`[0015] FIG. 4 shoWs an access procedure for forWard han
`dover.
`[0016] FIG. 5 shoWs an access procedure for basic han
`dover.
`[0017] FIGS. 6 and 7 shoW a process and an apparatus,
`respectively, for performing system access by the UE.
`[0018] FIGS. 8 and 9 shoW a process and an apparatus,
`respectively, for supporting system access by the Node B.
`[0019] FIGS. 10 and 11 shoW another process and appara
`tus, respectively, for performing system access by the UE.
`[0020] FIGS. 12 and 13 shoW another process and appara
`tus, respectively, for supporting system access by the Node B.
`[0021] FIGS. 14 and 15 shoW yet another process and appa
`ratus, respectively, for performing system access by the UE.
`[0022] FIGS. 16 and 17 shoW yet another process and appa
`ratus, respectively, for supporting system access by the Node
`B.
`
`DETAILED DESCRIPTION
`
`[0023] The techniques described herein may be used for
`various Wireless communication systems such as CDMA,
`TDMA, FDMA, OFDMA, SC-FDMA and other systems.
`The terms “system” and “netWor ” are often used inter
`changeably. A CDMA system may implement a radio tech
`nology such as Universal Terrestrial Radio Access (UTRA),
`cdma2000, etc. UTRA includes Wideband-CDMA
`(W-CDMA) and other CDMA variants. cdma2000 covers
`IS-2000, IS-95 and IS-856 standards. A TDMA system may
`implement a radio technology such as Global System for
`Mobile Communications (GSM). An OFDMA system may
`implement a radio technology such as Evolved UTRA
`(E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11
`(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash
`OFDM®, etc. UTRA, E-UTRA and GSM are part of Univer
`sal Mobile Telecommunication System (UMTS). 3GPP Long
`Term Evolution (LTE) is an upcoming release of UMTS that
`uses E-UTRA, Which employs OFDMA on the doWnlink and
`SC-FDMA on the uplink. UTRA, E-UTRA, GSM, UMTS
`and LTE are described in documents from an organiZation
`named “3rd Generation Partnership Project” (3GPP).
`
`Page 12 of 20
`
`

`
`US 2010/0093386 A1
`
`Apr. 15,2010
`
`cdma2000 and UMB are described in documents from an
`organization named “3rd Generation Partnership Project 2”
`(3GPP2). These various radio technologies and standards are
`knoWn in the art. For clarity, certain aspects of the techniques
`are described below for system access in LTE, and 3GPP
`terminology is used in much of the description beloW.
`[0024] FIG. 1 shoWs a Wireless multiple-access communi
`cation system 100 With multiple Node Bs 110. A Node B may
`be a ?xed station used for communicating With the UEs and
`may also be referred to as an evolved Node B (eNB), a base
`station, an access point, etc. Each Node B 110 provides com
`munication coverage for a particular geographic area. The
`overall coverage area of each Node B 110 may be partitioned
`into multiple (e.g., three) smaller areas. In 3GPP, the term
`“cell” can refer to the smallest coverage area of a Node B
`and/or a Node B subsystem serving this coverage area. In
`other systems, the term “sector” can refer to the smallest
`coverage area and/or the subsystem serving this coverage
`area. For clarity, 3GPP concept of cell is used in the descrip
`tion beloW.
`[0025] UEs 120 may be dispersed throughout the system. A
`UE may be stationary or mobile and may also be referred to as
`a mobile station, a terminal, an access terminal, a subscriber
`unit, a station, etc. A UE may be a cellular phone, a personal
`digital assistant (PDA), a Wireless modem, a Wireless com
`munication device, a handheld device, a laptop computer, a
`cordless phone, etc. A UE may communicate With one or
`multiple Node Bs via transmissions on the doWnlink and
`uplink.
`[0026] A system controller 130 may couple to Node Bs 110
`and provide coordination and control for the Node Bs. System
`controller 130 may be a single netWork entity or a collection
`of netWork entities.
`[0027] FIG. 2 shoWs a block diagram ofa design ofNode B
`110 and UE 120, Which are one ofthe Node Bs and one ofthe
`UEs in FIG. 1. In this design, Node B 110 is equipped With T
`antennas 22611 through 2262, and UE 120 is equipped With R
`antennas 25211 through 25213 Where in general T21 and R21 .
`Each antenna may be a physical antenna or an antenna array.
`[0028] At Node B 110, a transmit (TX) data processor 220
`may receive traf?c data for one or more UEs from a data
`source 212. TX data processor 220 may process (e.g., format,
`encode, interleave, and symbol map) the traf?c data for each
`UE based on one or more modulation and coding schemes
`selected for that UE to obtain data symbols. TX data proces
`sor 220 may also receive and process signaling messages
`from a controller/processor 240 and provide signaling sym
`bols. TX data processor 220 may also generate and multiplex
`pilot symbols With the data and signaling symbols. A TX
`MIMO processor 222 may perform spatial processing on the
`data, signaling and/or pilot symbols based on direct MIMO
`mapping, precoding/beamforming, etc. A symbol may be
`sent from one antenna for direct MIMO mapping or from
`multiple antennas for precoding/beamforming. TX MIMO
`processor 222 may provide T output symbol streams to T
`modulators (MODs) 22411 through 2242. Each modulator 224
`may process its output symbol stream (e.g., for OFDM) to
`obtain an output chip stream. Each modulator 224 may fur
`ther condition (e.g., convert to analog, ?lter, amplify, and
`upconvert) its output chip stream to obtain a doWnlink signal.
`T doWnlink signals from modulators 22411 through 2242 may
`be transmitted via T antennas 22611 through 2262, respec
`tively.
`
`[0029] At UE 120, antennas 25211 through 252r may
`receive the doWnlink signals from Node B 110 and provide
`received signals to demodulators (DEMODs) 25411 through
`2541; respectively. Each demodulator 254 may condition
`(e.g., ?lter, amplify, doWnconvert, and digitize) its received
`signal to obtain samples and may further process the samples
`(e.g., for OFDM) to obtain received symbols. A MIMO detec
`tor 260 may perform MIMO detection on the received sym
`bols from all R demodulators 25411 through 254r and provide
`detected symbols. A receive (RX) data processor 262 may
`process (e.g., symbol demap, deinterleave, and decode) the
`detected symbols and provide decoded data to a data sink 264
`and decoded signaling messages to a controller/processor
`280.
`[0030] On the uplink, at UE 120, traf?c data from a data
`source 272 and signaling messages from controller/processor
`280 may be processed by a TX data processor 274, further
`processed by a TX MIMO processor 276, conditioned by
`modulators 25411 through 2541; and transmitted to Node B
`110. At Node B 110, the uplink signals from UE 120 may be
`received by antennas 226, conditioned by demodulators 224,
`detected by a MIMO detector 230, and processed by an RX
`data processor 232 to obtain the traf?c data and signaling
`messages transmitted by UE 120.
`[0031] Controllers/processors 240 and 280 may direct the
`operation at Node B 110 and UE 120, respectively. Memories
`242 and 282 may store data and program codes for Node B
`110 and UE 120, respectively. A scheduler 244 may schedule
`UEs for doWnlink and/or uplink transmission and may pro
`vide assignments of resources for the scheduled UEs.
`[0032] FIG. 3 shoWs a design of an initial access procedure
`300. UE 120 may transmit a random access preamble on a
`Random Access Channel (RACH) Whenever the UE desires
`to access the system, e.g., at poWer up, if the UE has data to
`send, if the UE is paged by the system, etc. A random access
`preamble is a message that is sent ?rst for system access and
`may also be referred to as Message 1, an access signature, an
`access probe, a random access probe, a signature sequence, a
`RACH signature sequence, etc. The random access preamble
`may include various types of information and may be sent in
`various manners, as described beloW.
`[0033] Node B 110 may receive the random access pre
`amble from UE 120 and may respond by sending a random
`access response to UE 120. A random access response may
`also be referred to as Message 2, an access grant, an access
`response, etc. The random access response may carry various
`types of information and may be sent in various manners, as
`described beloW. UE 120 may receive the random access
`response and may send Message 3 for Radio Resource Con
`trol (RRC) connection request. Message 3 may contain vari
`ous types of information as described beloW. Node B 110 may
`respond With Message 4 for RRC contention resolution. Node
`B 110 may also send a message for RRC connection setup,
`etc. UE 120 and Node B 110 may thereafter exchange data.
`[0034] FIG. 3 shoWs a generic message How for system
`access. In general, each message may carry various types of
`information and may be sent in various manners.
`[0035] The system may support one set of transport chan
`nels for the doWnlink and another set of transport channels for
`the uplink. These transport channels may be used to provide
`information transfer services to Medium Access Control
`(MAC) and higher layers. The transport channels may be
`described by hoW and With What characteristics information is
`sent over a radio link. The transport channels may be mapped
`
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`to physical channels, which may be de?ned by various
`attributes such as modulation and coding, mapping of data to
`resource blocks, etc. The transport channels may include a
`Downlink Shared Channel (DL-SCH) used to send data to the
`UEs, an Uplink Shared Channel (UL-SCH) used to send data
`by the UEs, one or more RACHs used by the UEs to access the
`system, etc. The DL-SCH may also be referred to as a Down
`link Shared Data Channel (DL-SDCH) and may be mapped to
`a Physical Downlink Shared Channel (PDSCH). The UL
`SCH may also be referred to as an Uplink Shared Data Chan
`nel (UL-SDCH) and may be mapped to a Physical Uplink
`Shared Channel (PUSCH). The RACHs may be mapped to a
`Physical Random Access Channel (PRACH).
`[0036] Message 1 in FIG. 3 may carry the random access
`preamble and may include L bits of information, where L may
`be any integer value. Message 1 may include any of the
`following:
`[003 7] Random identi?er (ID)ia pseudo -random value
`selected by UE 120,
`[0038] Access typeiindicate initial system access or
`handover,
`[0039] Channel quality indicator (CQDiused to more
`e?iciently send Message 2,
`[0040] Power headroom informationiused to control
`transmission of Message 3,
`[0041] Buffer siZe informationiused to control trans
`mission of Message 3, and
`[0042] Other information.
`[0043] The random ID may be used to identify UE 120
`during system access but may not be unique since multiple
`UEs may select the same random ID. In case of collision in the
`random ID, contention may be resolved using a contention
`resolution procedure.
`[0044] The CQI may indicate the downlink channel quality
`as measured by UE 120 and may be used to send subsequent
`downlink transmission to the UE and/or to assign uplink
`resources to the UE. The CQI may be conveyed with 1 bit, 2
`bits, or some other number of bits. In general, the advantage
`of sending the CQI in Message 1 may be greater when Mes
`sage 2 is larger. The inclusion of the CQI in Message 1 may
`also enable grouping of random access preambles from dif
`ferent UEs based on their CQIs and hence better power con
`trol of Message 2 sent to these UEs. If Message 2 is relatively
`small and Message 4 is large, then the CQI may be sent in
`Message 3 instead of Message 1.
`[0045] Power headroom information may be included in
`Message 1 and may convey the available transmit power at
`UE 120. In one design, the power headroom information
`comprises a single bit that indicates whether the difference
`between the maximum transmit power at UE 120 and the
`transmit power used by the UE for Message 1 is above a
`threshold (e.g., 5 dB or some other value). In another design,
`the power headroom information comprises multiple bits and
`indicates the difference between the maximum transmit
`power at UE 120 and the transmit power used for Message 1.
`[0046] The power headroom information in addition to the
`receivedpower of Message 1 may more information than path
`loss alone. As an example, two UEs may measure the same
`path loss for a given Node B, and may send their Message 1
`with the same transmit power. However, a UE with a maxi
`mum transmit power of 24 dBm would have more power
`headroom than a UE with a maximum transmit power of 21
`dBm. Hence, UE 120 may send the power headroom infor
`mation in Message 1 to Node B 110, and Node B 110 may use
`
`this information to control the transmission of Message 3 by
`UE 120, e.g., to assign uplink resources for Message 3.
`[0047] Buffer siZe information may be included in Message
`1 and may indicate the amount of data to send in Message 3 by
`UE 120. Message 3 may carry various types of information
`such as RRC messages, a radio environment report, etc., and
`may have a variable siZe. In one design, the buffer siZe and
`power headroom information may be sent separately using a
`suf?cient number of bits for each type of information. In
`another design, the buffer siZe and power headroom informa
`tion may be combined. For example, a larger Message 3 may
`be selected if UE 120 has su?icient transmit power and suf
`?cient amount of data, and a smaller Message 3 may be
`selected otherwise. In both designs, log2(N) bits may be used
`to support N different siZes for Message 3. In any case, the
`buffer siZe and/or power headroom information may allow
`Node B 110 to assign appropriate uplink resources for Mes
`sage 3.
`[0048] An access sequence may be selected from a pool of
`2L available access sequences and sent for the random access
`preamble in Message 1. In one design, L:6, and an access
`sequence may be selected from a pool of 64 access sequences
`and sent for a 6-bit random access preamble. An L-bit index
`of the selected access sequence may be referred to as an
`RA-preamble identi?er.
`[0049] In one design, which is referred to as access proce
`dure option 1, one or more of the following features may be
`supported:
`[0050] Message 2 is sent on both L1/L2 control and the
`DL-SCH,
`[0051] A Cell Radio Network Temporary Identi?er
`(C-RNTI) is assigned to UE 120 in Message 2,
`[0052] UE 120 is identi?ed based on a Random Access
`RNTI (RA-RNTI) before the C-RNTI is assigned,
`[0053] Message 3 has a dynamic siZe, and
`[0054] Message 4 (contention resolution) and RRC con
`nection setup may be merged.
`[0055] Option 1 may provide more ?exibility since Node B
`110 can respond to the random access preamble from UE 120
`with a large Message 2, which may be sent on both L1/L2
`control and the DL-SCH. L1/L2 control refers to a mecha
`nism used by Layer 1/Layer 2 for sending signaling/control
`information. L1/L2 control may be implemented with a
`Physical Downlink Control Channel (PDCCH), a Shared
`Downlink Control Channel (SDCCH), etc.
`[0056] The C-RNTI may be used to uniquely identify UE
`120 by Node B 110 and may be assigned to the UE during the
`access procedure (e.g., in Message 2 or 4) or at some other
`time. The C-RNTI may also be referred to as a MAC ID, etc.
`UE 120 may be identi?ed by a temporary ID until the C-RNTI
`is assigned. Multiple RACHs may be available, and UE 120
`may randomly select one of the available RACHs. Each
`RACH may be associated with a different RA-RNTI. During
`the system access, UE 120 may be identi?ed by a combina
`tion of the RA-preamble identi?er for the access sequence
`sent by the UE and the RA-RNTI of the selected RACH.
`[0057] Node B 110 may respond to Message 1 from UE 120
`with Message 2, which may be a large message capable of
`carrying various types of information. Node B 110 may con
`vey the following information to UE 120 in Message 2:
`[0058] Timing advance (~8 bits)iused to adjust the tim
`ing of UE 120,
`[0059] RA-RNTI (~16 bits)iidentify the RACH being
`responded to by Node B 110,
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`[0060] RA-preamble identi?er (6 bits)iidentify the
`random access preamble being responded to by Node B
`110, and
`[0061] Uplink resources (~24 bits)iidentify uplink
`resources allocated to UE 120.
`[0062] In addition, Message 2 may also include any of the
`following:
`[0063] C-RNTI (l6 bits)ithe C-RNTI assigned to UE
`120,
`[0064] MAC header (~8 bits),
`[0065] Message type (~8 bits),
`[0066] PoWer adjustment/power control information for
`Message 3 (~4-6 bits), and
`[0067] Other information such as CQI resources, etc.
`[0068] The C-RNTI may be assigned to UE 120 in Message
`2. Multiple UEs may send the same random access preamble
`on the same RACH and may thus collide. In case of collisions,
`these UEs may be assigned the same C-RNTI. HoWever, only
`the UE that successfully resolves contention Would retain the
`assigned C-RNTI While other UEs Would access the system
`again and obtain neW C-RNTIs When they repeat the access
`procedure. The C-RNTI may also be assigned to UE 120 in
`Message 4.
`[0069] The RA-RNTI may be used as a temporary UE ID
`before the C-RNTI is assigned to UE 120. The RA-RNTI may
`identify the RACH and not the random access preamble.
`Message 2 may be addressed to a particular RA-RNTI and
`may thus be broadcast in nature. Also, the use of the RA
`RNTI may imply that Message 2 is sent onboth L1/ L2 control
`and the DL-SCH since the capacity of L1/L2 control alone
`may be too small. If both L1/L2 control and the DL-SCH are
`used to send Message 2, then a bene?t of using the RA-RNTI
`is that a single L1/L2 control channel may be used to address
`multiple UEs Whose random access preambles Were success
`fully received on the associated RACH by Node B 110. HoW
`ever, these gains should be evaluated in light of the loW
`likelihood of receiving multiple random access preambles on
`the same RACH at Node B 110 given the fact that the system
`design should ensure that collisions on the RACHs are rela
`tively infrequently.
`[0070] Assignment of the C-RNTI in Message 2 in con
`junction With the use of the RA-RNTI for Message 2 may
`enable use of Hybrid Automatic Repeat Request (HARQ) for
`Message 4. HARQ is typically used for a unicast transmission
`to a single UE. HARQ may also be employed With the RA
`RNTI (Which identi?es a RACH) instead of the C-RNTI
`(Which identi?es a speci?c UE). In this case, the RA-RNTI is
`used to identify a single UE for a HARQ transmission of
`Message 4 to this UE.
`[0071] In another design, Which is referred to as access
`procedure option 2, one or more of the folloWing features may
`be supported:
`[0072] Message 2 is sent on L1/L2 control,
`[0073] C-RNTI is assigned to UE 120 in Message 4 or
`later,
`[0074] UE 120 is identi?ed by an Implicit RNTI
`(I-RNTI) before the C-RNTI is assigned,
`[0075] Message 3 may have a static or dynamic siZe, and
`[0076] Message 4 (contention resolution) and RRC con
`nection setup may be merged.
`[0077] Option 2 may be spectrally ef?cient and may alloW
`Node B 110 to respond to the random access preamble from
`UE 120 With a spectrally ef?cient Message 2 sent using an
`L1/L2 control message. Since the L1/L2 control message
`
`may be relatively small, an uplink resource grant may be
`restricted in order to make room for timing advance and/or
`other information. UE 120 may be identi?ed by an I-RNTI
`before the C-RNTI is assigned to the UE. The I-RNTI may be
`formed based on (i) the RA-preamble identi?er and system
`time at the time of system access by UE 120, (ii) the selected
`RACH and the RA-preamble identi?er, or (iii) a combination
`of the selected RACH, the RA-preamble identi?er, the system
`time, etc. The I-CRNTI may occupy a portion (e.g., several
`percent) of the total space for the C-RNTI.
`[0078] Node B 110 may convey the folloWing information
`to UE 120 in Message 2:
`[0079] Timing advance (~8 bits),
`[0080] RA-preamble identi?er (0 bits)ipart of the
`I-CRNTI for UE 120, and
`[0081] Location of uplink resources (~5 bits)isuf?cient