US008599706B2
`
`(12) United States Patent
`Damnjanovic et a1.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 8,599,706 B2
`Dec. 3, 2013
`
`(54)
`
`(75)
`
`RANDOM ACCESS SIGNALING
`TRANSMISSION FOR SYSTEM ACCESS IN
`WIRELESS COMMUNICATION
`
`Inventors: Aleksandar Damnjanovic, San Diego,
`CA (US); Juan Montoj 0, San Diego,
`CA (US); Durga Prasad Malladi, San
`Diego, CA (US)
`
`(73)
`
`Assignee: QUALCOMM Incorporated, San
`Diego, CA (US)
`
`(*)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 859 days.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`6,738,366 B1
`7,054,298 B1
`
`5/2004 Etemad et a1.
`5/2006 Kim et a1.
`(Continued)
`
`FOREIGN PATENT DOCUMENTS
`
`DE
`EP
`
`9/2006
`102005011426
`5/2005
`1531644
`(Continued)
`OTHER PUBLICATIONS
`
`(21)
`
`(22)
`
`(86)
`
`(87)
`
`(65)
`
`(60)
`
`(51)
`
`(52)
`
`(58)
`
`Appl. N0.:
`
`12/439,716
`
`PCT Filed:
`
`Oct. 3, 2007
`
`PCT No.:
`
`PCT/US2007/080319
`
`§ 371 (0X1)’
`(2), (4) Date:
`
`Jun. 5, 2009
`
`PCT Pub. No.: WO2008/042967
`
`PCT Pub. Date: Apr. 10, 2008
`
`Prior Publication Data
`
`US 2010/0309877 A1
`Dec. 9, 2010
`Related US. Application Data
`
`Provisional application No. 60/828,058, ?led on Oct.
`3, 2006.
`
`Int. Cl.
`H04J1/16
`US. Cl.
`USPC ......... .. 370/252; 370/278; 370/311; 455/522;
`455/69; 455/127.1
`
`(2006.01)
`
`Field of Classi?cation Search
`USPC ....... .. 370/329, 335, 418, 330, 336, 282, 278,
`370/252, 311; 455/522, 69, 63.1
`See application ?le for complete search history.
`
`ETSI: “3GPP TR 25.814 v 7.0.0, Physical layer aspects for evolved
`Universal Terrestrial Radio Access (UTRA)” 3rd Generation Part
`nership Project, Jun. 15, 2006, p. 1-5, 67-107, XP002481722.
`(Continued)
`
`Primary Examiner * Dady Chery
`(74) Attorney, Agent, or Firm * Ashish L. Patel
`
`ABSTRACT
`(57)
`Techniques for transmitting random access signaling for sys
`tem access are described. In an aspect, random access signal
`ing may be sent based on at least one transmission parameter
`having different values for different user equipment (UE)
`classes. At least one parameter value may be determined
`based on a particular UE class, and the random access signal
`ing may be sent based on the determined parameter value(s).
`The random access signaling may be a random access pre
`amble, and the at least one transmission parameter may
`include a target SNR, a backoff time, and/or a poWer ramp.
`The random access preamble may then be sent based on a
`target SNR value, a poWer ramp value, and/or a backoff time
`value for the particular UE class. In another aspect, a message
`for system access may be sent based on a poWer control
`correction received in a random access response for the ran
`dom access preamble.
`
`33 Claims, 8 Drawing Sheets
`
`UE
`
`eNB
`
`300
`r,
`
`A1
`
`Random access preamble (Random ID, etc.)
`
`> no HARQ
`
`A2 :
`
`PDCCHlPDSCl-l (Timing advance'UL resources,
`PC correction, CRC XORed with l-RNTI)
`
`no H ARQ
`
`A3
`
`Unique UE 1D, CQI, measurement report, etc.
`
`: HARQ
`
`M :
`
`PDCCH (l-RNTI, DL resources, etc.)
`
`A5 : PDSCH (Unique UE ID, C-RNTI, CQI resources, PC resources, etc.)
`
`HARQ
`
`HARQ
`
`A6
`
`A7 :
`
`AB =
`
`Layer 3 signaling (NAS messages)
`
`: HARQ
`
`Layer 3 signaling (NAS messages)
`
`HARQ
`
`Data
`
`> H ARQ
`
`Page 1 of 20
`
`LG Electronics Exhibit 1003
`
`

`
`US 8,599,706 B2
`Page 2
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`2002/0077138 A1* 6/2002 Bark et al. .................. .. 455/522
`2004/0032877 A1 *
`2/2004 Chuah et a1~
`~ 370/444
`2004/0147274 A1 *
`7/2004 Khawand et al' """""" " 455/522
`2006/0111104 A1
`5/2006 Hyslop _
`2011/0230199 A1* 9/2011 Patabandi et al. ........... .. 455/450
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`
`JP
`JP
`JP
`RU
`
`1555765
`2000209661 A
`2002524990 A
`2002539707
`2006515737 A
`2191479 C2
`
`7/2005
`7/2000
`8/2002
`11/2002
`6/2006
`10/2002
`
`RU
`WO
`W0
`
`2209528 C2
`WO9637079
`9824250
`
`7/2003
`11/1996
`6/1998
`
`OTHER PUBLICATIONS
`
`Texas Instruments: “Random Access usage for RRC state transitions
`and mobility support” 3GPP Draft; R2-060852, 3rd Generation Part
`nership Project (3GPP), Mobile Competence Centre; 650; Route
`DES Lucioles; F-06921 Sophia-Antipolis Cedex, France, vol. tsL
`ran\WG2iRL2\TSGRZiS2\Documents\JointiR1iR2, no Athens,
`Greece; 20060327, Mar. 20, 2006, XP050131002.
`International Search RepoItiPCT/US2007/080319, International
`Search AuthorityiEuropean Patent Of?ceiJan. 13, 2009.
`Written OpinioniPCT/U S2007/ 080319, International Search
`AuthorityiEuropean Patent Of?ceiJan. 13, 2009.
`Taiwan Search RepoItiTW096137087iTIPOiApr. 22, 2011.
`
`* cited by examiner
`
`Page 2 of 20
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`

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`US. Patent
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`Dec. 3, 2013
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`Sheet 8 0f 8
`
`US 8,599,706 B2
`
`Start
`l
`Determine at least one parameter
`value for at least one transmission
`parameter for random access
`signaling based on a particular UE
`class, the at least one transmission
`parameter having different values
`for a plurality of UE classes
`l
`Send the random access
`signaling based on the at least one
`parameter value for system access
`i
`End
`
`800
`) e
`
`900
`r“
`[912
`Module to determine at least one
`parameter value for at least one
`transmission parameter for random
`access signaling based on a particular
`UE class, the at least one transmission
`parameter having different values
`for a plurality of UE classes
`,914
`I
`Module to send the random access
`signaling based on the at least one
`parameter value for system access
`
`(
`
`D
`
`FIG. 9
`
`FIG. 8
`
`St rt
`a.
`l,
`
`[1012
`
`<
`
`1000
`e
`
`Send a random access
`preamble for system access
`l
`,1014
`
`Receive a random access
`response with a PC correction
`l
`,1016
`Determine transmit power of a
`message based on the PC correction
`and possibly other parameters
`l
`,1018
`Send the message with the
`determined transmit power
`l
`End
`
`)
`
`FIG. 10
`
`1100
`e
`,1112
`Module to send a random access
`preamble for system access
`|
`,1114
`Module to receive a random access
`response with a PC correction
`|
`,1116
`Module to determine transmit
`power of a message based
`on the PC correction and
`possibly other parameters
`,1118
`[
`Module to send the message
`with the determined transmit power
`
`FIG. 11
`
`Page 10 of 20
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`

`
`US 8,599,706 B2
`
`1
`RANDOM ACCESS SIGNALING
`TRANSMISSION FOR SYSTEM ACCESS IN
`WIRELESS COMMUNICATION
`
`The present application claims priority to provisional US.
`Application Ser. No. 60/828,058, ?led Oct. 3, 2006, and
`assigned to the assignee hereof and incorporated herein by
`reference.
`
`BACKGROUND
`
`2
`poWer. In another design, the at least one transmission param
`eter may comprise a backoff time, and the amount of time to
`Wait betWeen successive transmissions of the random access
`preamble may be determined based on a backoff time value
`for the particular UE class. In yet another design, the at least
`one transmission parameter may comprise a poWer ramp, and
`the transmit poWer for successive transmissions of the ran
`dom access preamble may be determined based on a poWer
`ramp value for the particular UE class.
`In another design, the random access signaling may be a
`message sent after receiving a random access response for the
`random access preamble. The at least one transmission
`parameter may comprise a poWer offset betWeen a ?rst chan
`nel used to send the random access preamble and a second
`channel used to send the message. The transmit poWer of the
`message may be determined based on a poWer offset value for
`the particular UE class, and the message may be sent With the
`determined transmit poWer.
`In another aspect, a message for system access may be sent
`based on a poWer control (PC) correction. A random access
`preamble may be sent for system access, and a random access
`response With a PC correction may be received. The transmit
`poWer of the message may be determined based on the PC
`correction and other parameters such as the poWer offset
`betWeen the channels used to send the random access pre
`amble and the message. The message may then be sent With
`the determined transmit poWer.
`Various aspects and features of the disclosure are described
`in further detail beloW.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 shoWs a Wireless multiple-access communication
`system.
`FIG. 2 shoWs a transmission structure for the uplink.
`FIG. 3 shoWs a message How for initial system access.
`FIG. 4 shoWs a message How for system access to transition
`to an active state.
`FIG. 5 shoWs a message How for system access for han
`dover.
`FIG. 6 shoWs successive random access preamble trans
`missions With backoff.
`FIG. 7 shoWs a block diagram of an eNB and a UE.
`FIG. 8 shoWs a process for transmitting random access
`signaling.
`FIG. 9 shoWs an apparatus for transmitting random access
`signaling.
`FIG. 10 shoWs a process for transmitting a message for
`system access.
`FIG. 11 shoWs an apparatus for transmitting a message for
`system access.
`
`DETAILED DESCRIPTION
`
`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 interchangeably. A
`CDMA system may implement a radio technology such as
`Universal Terrestrial Radio Access (UTRA), cdma2000, etc.
`UTRA includes Wideband-CDMA (W-CDMA) and LoW
`Chip Rate (LCR). cdma2000 covers IS-2000, IS-95 and
`IS-856 standards. A TDMA system may implement a radio
`technology such as Global System for Mobile Communica
`tions (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
`
`I. Field
`The present disclosure relates generally to communication,
`and more speci?cally to techniques for accessing a Wireless
`communication system.
`II. Background
`Wireless communication systems are Widely deployed to
`provide various communication content such as voice, video,
`packet data, messaging, broadcast, etc. These Wireless sys
`tems 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
`Multiple Access (TDMA) systems, Frequency Division Mul
`tiple Access (FDMA) systems, Orthogonal FDMA
`25
`(OFDMA) systems, and Single-Carrier FDMA (SC-FDMA)
`systems.
`A Wireless communication system may include any num
`ber of base stations that can support communication for any
`number of user equipments (U Es). Each UE may communi
`cate With one or more base stations via transmissions on the
`doWnlink and uplink. The doWnlink (or forward link) refers to
`the communication link from the base stations to the UEs, and
`the uplink (or reverse link) refers to the communication link
`from the UEs to the base stations.
`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 base station may receive the random access pre
`amble and respond With a random access response (or an
`access grant) that may contain pertinent information for the
`UE. Uplink resources are consumed to transmit the random
`access preamble, and doWnlink resources are consumed to
`transmit the random access response. Furthermore, the ran
`dom access preamble and other signaling sent for system
`access may cause interference on the uplink. There is there
`fore a need in the art for techniques to e?iciently transmit the
`random access preamble and signaling for system access.
`
`20
`
`30
`
`35
`
`40
`
`45
`
`SUMMARY
`
`Techniques for ef?ciently transmitting random access sig
`naling for system access are described herein. In an aspect, a
`UE may send random access signaling based on at least one
`transmission parameter having different values for different
`UE classes, Which may provide certain advantages described
`beloW. At least one parameter value for the at least one trans
`mission parameter may be determined based on a particular
`UE class. The random access signaling may then be sent
`based on the at least one parameter value for system access.
`In one design, the random access signaling may be a ran
`dom access preamble, Which is signaling sent ?rst for system
`access. The at least one transmission parameter may comprise
`a target signal-to-noise ratio (SNR) for the random access
`preamble. The transmit poWer of the random access preamble
`may be determined based on a target SNR value for the
`particular UE class and other parameters. The random access
`preamble may then be sent With the determined transmit
`
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`US 8,599,706 B2
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`3
`(WiMAX), IEEE 802.20, Flash-OFDM®, etc. UTRA,
`E-UTRA and GSM are part of Universal Mobile Telecom
`munication 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). 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 LTE termi
`nology is used in much of the description beloW.
`FIG. 1 shoWs a Wireless multiple-access communication
`system 100 With multiple evolved Node Bs (eNBs) 110. An
`eNB may be a ?xed station used for communicating With the
`UEs and may also be referred to as a Node B, a base station,
`an access point, etc. Each eNB 110 provides communication
`coverage for a particular geographic area. The overall cover
`age area of each eNB 110 may be partitioned into multiple
`(e. g., three) smaller areas. In 3GPP, the term “cell” can refer
`to the smallest coverage area, of an eNB and/or an eNB
`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 description beloW.
`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
`more eNBs via transmissions on the doWnlink and uplink. In
`FIG. 1, a solid line With double arroWs indicates communi
`cation betWeen an eNB and a UE. A broken line With a single
`arroW indicates a UE attempting to access the system.
`FIG. 2 shoWs an example transmission structure for the
`uplink. The transmission timeline may be partitioned into
`units of radio frames. Each radio frame may be partitioned
`into multiple (S) subframes, and each subframe may include
`multiple symbol periods. In one design, each radio frame has
`a duration of 10 milliseconds (ms) and is partitioned into 10
`subframes, and each subframe has a duration of 1 ms and
`includes 12 or 14 symbol periods. The radio frames may also
`be partitioned in other manners.
`The time-frequency resources available for the uplink may
`be allocated for different types of transmission such as tra?ic
`data, signaling/control information, etc. In one design, one or
`more Random Access Channel (RACH) slots may be de?ned
`in each radio frame and may be used by the UEs for system
`access. In general, any number of RACH slots may be
`de?ned. Each RACH slot may have any time-frequency
`dimension and may be located anyWhere Within a radio
`frame. In one design that is shoWn in FIG. 2, a RACH slot
`spans one subframe and covers a predetermined bandWidth of
`1.25 MHZ. The RACH slot location (e.g., the speci?c sub
`frame and portion of the system bandWidth used for the
`RACH slot) may be conveyed in system information that is
`broadcast on a Broadcast Channel (BCH) by each cell. Other
`parameters for the RACH slot (e.g., signature sequences
`being used) may be ?xed or conveyed via the system infor
`mation.
`The system may support one set of transport channels for
`the doWnlink and another set of transport channels for the
`uplink. These transport channels may be used to provide
`
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`30
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`35
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`
`4
`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
`to physical channels, Which may be de?ned by various
`attributes such as modulation and coding, mapping of data to
`resource blocks, etc. Table 1 lists some physical channels
`used for the doWnlink (DL) and uplink (U L) in LTE in accor
`dance With one design.
`
`TABLE 1
`
`Link Channel Channel Name
`
`Description
`
`Carry system information
`DL PBCH Physical Broadcast
`broadcast over a cell.
`Channel
`DL PDCCH Physical DoWnlink Carry UE-speci?c control
`Control Channel
`information for the PDSCH.
`DL PDSCH Physical DoWnlink Carry data for UEs in a shared
`Shared Channel
`manner.
`UL PRACH Physical Random
`Carry random access preambles
`Access Channel
`from UEs attempting to access
`the system.
`Carry control information from
`UEs such as CQI, ACIQNAK,
`resource requests, etc.
`Carry data sent by a UE on uplink
`resources assigned to the UE.
`
`UL PUCCH Physical Uplink
`Control Channel
`
`UL PUSCH Physical Uplink
`Shared Channel
`
`The physical channels in Table 1 may also be referred to by
`other names. For example, the PDCCH may also be referred
`to as a Shared DoWnlink Control Channel (SDCCH), Layer
`l/Layer 2 (Ll/L2) control, etc. The PDSCH may also be
`referred to as a doWnlink PDSCH (DL-PDSCH). The PUSCH
`may also be referred to as an uplink PDSCH (UL-PDSCH).
`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, a
`RACH used by the UEs to access the system, etc. The DL
`SCH may be mapped to the PDSCH and may also be referred
`to as a DoWnlink Shared Data Channel (DL-SDCH). The
`UL-SCH may be mapped to the PUSCH and may also be
`referred to as an Uplink Shared Data Channel (UL-SDCH).
`The RACH may be mapped to the PRACH.
`A UE may operate in one of several states such as LTE
`Detached, LTE Idle and LTE Active states, Which may be
`associated With RRC_NULL, RRC_IDLE and RRC_CON
`NECTED states, respectively. Radio Resource Control
`(RRC) may perform various functions for establishment,
`maintenance and termination of calls. In the LTE Detached
`state, the UE has not accessed the system and is not knoWn by
`the system. The UE may poWer up in the LTE Detached state
`and may operate in the RRC_NULL state. The UE may tran
`sition to either the LTE Idle state or LTE Active state upon
`accessing the system and performing registration. In the LTE
`Idle state, the UE may have registered With the system but
`may not have any data to exchange on the doWnlink or uplink.
`The UE may thus be idle and operate in the RRC_IDLE state.
`In the LTE Idle state, the UE and the system may have perti
`nent context information to alloW the UE to quickly transition
`to the LTE Active state. The UE may transition to the LTE
`Active state When there is data to send or receive. In the LTE
`Active state, the UE may actively communicate With the
`system on the doWnlink and/or uplink and may operate in the
`RRC_CONNECTED state.
`The UE may transmit a random access preamble on the
`uplink 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 signaling that is
`sent ?rst for system access and may also be referred to as an
`
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`US 8,599,706 B2
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`5
`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 infor
`mation and may be sent in various manners, as described
`beloW. An eNB may receive the random access preamble and
`may respond by sending a random access response to the UE.
`A random access response may also be referred to as 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. The UE and eNB
`may further exchange signaling to set up a radio connection
`and may thereafter exchange data.
`FIG. 3 shoWs a message How for a design of a random
`access procedure 300. In this design, the UE may be in the
`RRC_NULL or RRC_IDLE state and may access the system
`by sending a random access preamble (step A1). The random
`access preamble may include L bits of information, Where L
`may be any integer value. An access sequence may be
`selected from a pool of 2L available access sequences and sent
`for the random access preamble. In one design, the random
`access preamble includes L:6 bits of information, and one
`access sequence is selected from a pool of 64 access
`sequences. The 2L access sequences may be of any length and
`may be designed to have good detection properties. For
`example, 64 access sequences may be de?ned based on dif
`ferent cyclic shifts of a Zardoff-Chu sequence of a suitable
`length.
`The random access preamble may include a random iden
`ti?er (ID) that may be pseudo-randomly selected by the UE
`and used to identify the random access preamble from the UE.
`The random access preamble may also include one or more
`additional bits for doWnlink channel quality indicator (CQI)
`and/ or other information. The doWnlink CQI may be indica
`tive of the doWnlink channel quality as measured by the UE
`and may be used to send subsequent doWnlink transmission to
`the UE and/or to assign uplink resources to the UE. In one
`design, a 6-bit random access preamble may include a 4-bit
`random ID and a 2-bit CQI. In another design, a 6-bit random
`access preamble may include a 5-bit random ID and a 1-bit
`CQI. The random access preamble may also include different
`and/ or additional information.
`The UE may determine an Implicit Radio Network Tem
`porary Identi?er (I-RNTI) that may be used as a temporary ID
`for the UE during system access. The UE may be identi?ed by
`the I-RNTI until a more permanent ID such as a Cell RNTI
`(C-RNTI) is assigned to the UE. In one design, the I-RNTI
`may include the folloWing:
`System time (8 bits)itime When the access sequence is
`sent by the UE, and
`RA-preamble identi?er (6 bits)iindex of the access
`sequence sent by the UE.
`The I-RNTI may have a ?xed length (e. g., 16 bits) and may
`be padded With a su?icient number of Zeros (e.g., 2 Zeros) to
`achieve the ?xed length. The system time may be given in
`units of radio frames, and an 8-bit system time may be unam
`biguous over 256 radio frames or 2560 ms. In another design,
`the I-RNTI is composed of 4-bit system time, 6-bit RA
`preamble identi?er, and padding bits (if needed). In general,
`the I-RNTI may be formed With any information that may (i)
`alloW the UE or random access preamble to be individually
`addressed and (ii) reduce the likelihood of collision With
`another UE using the same I-RNTI. The lifetime of the
`I-RNTI may be selected based on the maximum expected
`response time for an asynchronous response to the random
`access preamble. The I-RNTI may also include system time
`and a pattern (e.g., 000 .
`.
`. 0 in front of system time) to
`indicate that the RNTI addresses the RACH.
`
`40
`
`45
`
`5
`
`20
`
`25
`
`30
`
`35
`
`50
`
`55
`
`60
`
`65
`
`6
`In another design, multiple RACHs may be available, and
`the UE may randomly select one of the available RACHs.
`Each RACH may be associated With a different Random
`Access RNTI (RA-RNTI). The UE may be identi?ed by a
`combination of the RA-preamble identi?er and the RA-RNTI
`of the selected RACH during the system access. An I-RNTI
`may be de?ned based on any combination of the RA-pre
`amble identi?er, RA-RNTI, and system time, e.g., the RA
`preamble identi?er and RA-RNTI, or the RA-RNTI and sys
`tem time, etc. System time may be bene?cial for
`asynchronous response to the random access preamble. If the
`I-RNTI is formed based on the RA-RNTI and system time,
`then the UE may be identi?ed based on the RA-preamble
`identi?er sent separately, e.g., on the PDSCH. The UE may
`send the random access preamble on the selected RACH.
`An eNB may receive the random access preamble from the
`UE and may respond by sending a random access response on
`the PDCCH and/or PDSCH to the UE (step A2). The eNB
`may determine the I-RNTI of the UE in the same manner as
`the UE. The eNB may asynchronously respond to the random
`access preamble from the UE Within the lifetime of the
`I-RNTI. In one design, the PDCCH/PDSCH may carry the
`folloWing:
`Timing advanceiindicate adjustment to the transmit tim
`ing of the UE,
`UL resourcesiindicate resources granted to the UE for
`uplink transmission,
`PC correctioniindicate adjustment to the transmit poWer
`of the UE, and
`I-RNTIiidentify the UE or access attempt for Which the
`access grant is sent.
`A cyclic redundancy check (CRC) may be generated based
`on all information being sent on the PDCCH/PDSCH. The
`CRC may be exclusive ORed @(ORed) With the I-RNTI (as
`shoWn in FIG. 3), the RA-preamble identi?er, the RA-RNTI,
`and/or other information to identify the UE being addressed.
`Different and/or other information may also be sent on the
`PDCCH/PDSCH in step A2.
`The UE may then respond With a unique UE ID in order to
`resolve possible collision (step A3). The unique UE ID may
`be an International Mobile Subscriber Identity (IMSI), a
`Temporary Mobile Subscriber Identity (TMSI), another ran
`dom ID, etc. The unique UE ID may also be a registration area
`ID if the UE has already registered in a given area. The UE
`may also send doWnlink CQI, pilot measurement report, etc.,
`along With the unique UE ID.
`The eNB may receive a unique “handle” or pointer to the
`unique UE ID. The eNB may then assign a C-RNTI and
`control channel resources to the UE. The eNB may send a
`response on the PDCCH and PDSCH (steps A4 and A5). In
`one design, the PDCCH may carry a message containing the
`I-RNTI and DL resources indicating Where remaining infor
`mation is sent on the PDSCH to the UE. In one design, the
`PDSCH may carry a message containing the unique UE ID,
`the C-RNTI (if assigned), CQI resources used by the UE to
`send doWnlink CQI, PC resources used to send PC correc
`tions to the UE, etc. The messages sent on the PDCCH and
`PDSCH may also carry different and/or other information.
`The UE may decode the messages sent on the PDCCH and
`PDSCH to the UE. After decoding these tWo messages, the
`UE has su?icient resources con?gured and can exchange
`Layer 3 signaling With the eNB (steps A6 andA7). The Layer
`3 signaling may include Non-Access Stratum (NAS) mes
`sages for authentication of the UE, con?guration of the radio
`link betWeen the UE and eNB, connection management, etc.
`The UE and eNB may exchange data after completing the
`Layer 3 signaling (step A8).
`
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`7
`FIG. 4 shows a message How for a design of a random
`access procedure 400. In this design, the UE may be in the
`RRC_IDLE or RRC_CONNECTED state and may already
`have a C-RNTI assigned to the UE. The UE may access the
`system from the RRC_IDLE state in response to receiving
`data to send or from the RRC_CONNECTED state in
`response to a handover command. The UE may send a ran
`dom access preamble, Which may include a random ID and
`possibly one or more additional bits for doWnlink CQI and/or
`other information (step B1).
`An eNB may receive the random access preamble from the
`UE and may respond by sending a random access response on
`the PDCCH and/or PDSCH to the UE (step B2). The random
`access response may include timing advance, UL resources,
`PC correction, and a CRC that may be XORed With an
`I-RNTI, an RA-preamble identi?er, an RA-RNTI, and/or
`other information to identify the UE. The UE may then send
`its C-RNTI, doWnlink CQI, pilot measurement report and/or
`other information to the eNB (step B3). The eNB may then
`send a response on the PDCCH and PDSCH (steps B4 and
`B5). The PDCCH may carry a message containing the
`C-RNTI and the DL resources for the PDSCH. The PDSCH
`may carry a message containing the CQI resources, PC
`resources, etc. The UE may decode the messages sent on the
`PDCCH and PDSCH to the UE. Layer 3 signaling exchanges
`may be omitted since the UE has been authenticated prior to
`being assigned the C-RNTI. After step B5, the UE has su?i
`cient resources con?gured and can exchange data With the
`eNB (step B6).
`FIG. 5 shoWs a message How for a design of a random
`access procedure 500 for handover. In this design, the UE
`may be communicating With a source eNB and may be
`handed over to a target eNB. The UE may be assigned a
`random ID by the source eNB foruse to access the target eNB.
`To avoid collision, a subset of all possible random IDs may be
`reserved for handover, and the random ID assigned to the UE
`may be selected from this reserved subset. Information
`regarding the subset of reserved random IDs may be broad
`cast to all UEs.
`The source eNB may inform the target eNB of the C-RNTI,
`random ID, CQI resources, PC resources and/or other infor
`mation for the UE. Collision resolution may not be necessary
`due to a one-to -one mapping betWeen the assigned random ID
`and the C-RNTI of the UE. The target eNB may thus have
`pertinent context information for the UE prior to the random
`access procedure. For simplicity, FIG. 5 shoWs the random
`access procedure betWeen the UE and the target eNB.
`The UE may send a random access preamble, Which may
`include the random ID assigned to the UE and possibly other
`information (step C1). The target eNB may receive the ran
`dom access preamble and may respond by sending a random
`access response on the PDCCH and/or PDSCH to the UE
`(step C2). The random access response may include timing
`advance, UL resources, PC correction, and a CRC that may be
`XORed With the C-RNTI of the UE. After step C2, the UE has
`suf?cient resources con?gured an