US008009637B2
`
`US 8,009,637 B2
`(10) Patent No.:
`az) United States Patent
`Harriset al.
`(45) Date of Patent:
`Aug. 30, 2011
`
`
`(54) METHOD AND APPARATUS FOR
`SPREADING CHANNEL CODE SELECTION
`Inventors: John M. Harris, Chicago, IL (US);
`Vijay G. Subramanian, Dublin (IE)
`
`(75)
`
`6,594,248 BL*
`7/2003 Karnaetal. .......8. 370/342
`
`6,741,582 B1*
`. 370/342
`5/2004 Mansour.........
`6,743,395 B2*
`we 419/23
`6/2004 Fukunagaetal.
`er2sHes B25 Mz006 i Chak, sxmmasneunanm Jottde
`(Continued)
`
`(73) Assignee: Motorola Solutions, Inc., Schaumburg,
`IL (US)
`
`
`
`FOREIGN PATENT DOCUMENTS
`1230748 Bl
`10/2005
`EP
`10-0389818 Bl
`7/2003
`KR
`
`(*) Notice: 2005018131 A2—2/2005Subject to any disclaimer, the term ofthis WO
`
`WO
`:
`:
`2006019710 Al
`2/2006
`patent is extended or adjusted under 35
`US.C. 154(b) by 867 days.
`
`OTHER PUBLICATIONS
`
`(21) Appl. No.: 11/624,428
`
`(22)
`
`Filed:
`
`Jan. 18, 2007
`
`(65)
`
`Prior Publication Data
`
`US 2007/0211787 Al
`
`Sep. 13, 2007
`
`Related U.S. Application Data
`(60) Provisional application No. 60/781,527,filed on Mar.
`10, 2006.
`
`(51)
`
`Int. Cl.
`(2006.01)
`HO4B 7/216
`(52) U.S.C..... 370/335; 455/450; 455/451; 455/452.2;
`455/453; 455/509; 370/209; 370/329; 370/341;
`370/342; 370/203; 370/330; 370/441; 375/130;
`375/133; 375/140; 375/141; 375/149
`(58) Field of Classification Search ........0......... 370/335,
`370/342, 431, 441, 208, 209, 203, 328, 329,
`370/330, 341; 455/67.11, 67.13, 436, 450,
`455/451, 452.1, 452.2, 69, 453, 509, 513;
`375/130, 133, 140, 141, 149
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`6,185,423 B1*
`6,522,658 BI*
`
`2/2001 Brownetal. wo... 455/434
`2/2003 Roccanova ..... ccc 370/441
`
`Blaine R. Copenheaver, “Corresponding Application PCT/US07/
`062377—PCTInternational Search Report and Written Opinion,”
`WIPO, ISA/US, Commissioner for Patents, Alexandria, VA, USA,
`Mar. 17, 2008, 11 pages, most relevant pp. 4-5 and 9-10.
`.
`(Continued)
`
`Primary Examiner — Olumide T Ajibade Akonai
`(74) Attorney, Agent, or Firm — Jeffrey K. Jacobs; Brian
`Mancini; Daniel R. Bestor
`
`ABSTRACT
`(57)
`Various embodiments are described which may serve to
`improve spreading channel code selection in wireless tech-
`nologies that employ two-stage ranging. For example, some
`ofthe embodiments enable a numberofspreading codes to be
`reused at each network node (111, 112), potentially increas-
`ing the numberof codes available to each remote unit and
`therebyreducing thecollision rate. Rather than simply select-
`ing a spreading channel code randomly, remote units (101-
`103), in some embodiments, select a spreading channel code
`based on one or more considerations such as pilot signal
`strength, remote unit location, a remote unit mobility level,
`and a priority class associated with the remote unit. Depend-
`ing on the embodiment, network nodes can partition the
`spreading codes into groups and then assign link bandwidth
`to remote units based on the group associated with the code
`selected by that remote unit.
`
`13 Claims, 5 Drawing Sheets
`
`00
`
`307
`
`303
`
`1
`
`}
`START
`{
`30
`v
` PARTITION SPREADING CHANNEL CODES INTO A NUMBER OF CODE GROUPS
`¥
`305
` TRANSMIT BY A NETWORK NODE SIGNALING THAT INDICATES
`
`
`
`THE CODE GROUPINGS PRODUCED BY THE PARTITIONING
`
`RECEIVE BY THE NETWORKNODEANINITIAL ACCESS SIGNAL FROMA REMOTE UNIT
`USING A SPREADING CHANNEL CODE FROM ONE OF THESE CODE GROUPS
`
`309
`
`END
`
`APPLE 1004
`APPLE1004
`
`

`

`US 8,009,637 B2
`
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`OTHER PUBLICATIONS
`
`2/2006 Chhedaet al.
`6,996,056 B2
`6/2006 Kimet al. scecccccsoe 370/335
`7.061.890 B2*
`
`8/2006 Horne ..........
`- 370/209
`7,088,673 B2*
`7,133,353 B2* 11/2006 Sourour etal.
`. 370/208
`7,450,556 B2* 11/2008 Shenetal.
`...
`. 370/342
`7,554,965 B2*
`6/2009 Karaoguz ..........
`. 370/342
`2003/0043774 A1*
`3/2003 Hamalainenet al.
`. 370/342
`2003/0112744 Al*
`6/2003 Baumetal. ........
`. 370/206
`
`2004/0071115 Al*
`4/2004 Earnshawet al.
`. 370/335
`2005/0002357 Al*
`1/2005 Huetal. wo. 370/332
`2005/0030931 Al
`2/2005 Sungetal.
`2005/0058058 Al*
`3/2005 Choetal. wn. 370/208
`3/2007 Muharemovicet al.
`2007/0060180 Al*
`.. 455/509
`
`.
`
`a
`
`an
`ali a :
`Nora Linder, Conespanding Application PCUUBZOOMGS2977
`PCTInternational Preliminary Report on Patentability,’ The Interna-
`tional Bureau ofWIPO, Geneva, Switzerland, Sep. 25, 2008, 7 pages,
`most relevantpp. 2, 6-7.
`:
`«
`’
`:
`os
`Pree
`nan Examines ee . om vreiminay Rejection
`orean Intellectual
`Property
`Ottice,
`Daejeon,
`Republic of
`Korea,
`May 31, 2010, 6 pages, most relevantpp. 1-2.
`Japanese Office Action Dated Apr. 19, 2011 for Counterpart Appli-
`cation.
`
`* cited by examiner
`
`

`

`U.S. Patent
`
`Aug. 30, 2011
`
`Sheet 1 of 5
`
`US8,009,637 B2
`
`—s ISio
`
`
`
`FIG.
`
`1
`
`

`

`U.S. Patent
`
`Aug. 30, 2011
`
`Sheet 2 of 5
`
`US8,009,637 B2
`
`—
`
`111 yy
`
`io
`
`M125
`NETWORK
`
`
`NETWORK
`
`PROCESSING)
`
`101
`
`UNIT
`
`REMOTE UNIT
`
`FIG. 2
`
`

`

`U.S. Patent
`
`Aug. 30, 2011
`
`Sheet 3 of 5
`
`US8,009,637 B2
`
`KeioiO
`
`307
`
`303
`
`30"
`
`START
`
`PARTITION SPREADING CHANNEL CODES INTO A NUMBER OF CODE GROUPS
`
`
` THE CODE GROUPINGS PRODUCED BY THE PARTITIONING
`
`305
`
`TRANSMIT BY A NETWORK NODESIGNALING THAT INDICATES
`
`RECEIVE BY THE NETWORK NODEANINITIAL ACCESS SIGNAL FROM A REMOTE UNIT
`USING A SPREADING CHANNEL CODE FROM ONE OF THESE CODE GROUPS
`
`309
`
`END
`
`FIG. 3
`
`

`

`U.S. Patent
`
`Aug. 30, 2011
`
`Sheet 4 of 5
`
`US8,009,637 B2
`
`ps oSiO
`
`403
`
`405
`
`401
`
`START
`
`
`
`RECEIVE BY A REMOTE UNIT SIGNALING FROM A NETWORK NODE
`
`SELECT BY THE REMOTE UNIT A SPREADING CHANNEL CODE BASED
`ON AT LEAST ONE OF THE FOLLOWING CONSIDERATIONS:
`
`
`
`A SIGNAL STRENGTH OF THE RECEIVED SIGNALING,
`A CURRENT LOCATION OF THE REMOTE UNIT,
`A CURRENT MOBILITY LEVEL OF THE REMOTE UNIT, AND
`A CURRENT PRIORITY CLASS ASSOCIATED WITH THE REMOTE UNIT
`
`407
`
`!
`
`TRANSMIT BY THE REMOTE UNIT AN INITIAL ACCESS SIGNAL
`USING THE SPREADING CHANNEL CODE SELECTING
`
`
`
`FIG. 4
`
`

`

`U.S. Patent
`
`Aug. 30, 2011
`
`Sheet 5 of 5
`
`US8,009,637 B2
`
`cn
`
`iO
`
`oo"
`
`START
`
`PARTITION SPREADING CHANNEL CODES INTO A NUMBER OF CODE GROUPS
`
`
`
`
`503
`
`505
`
`RECEIVE BY THE NETWORK NODEANINITIAL ACCESS SIGNAL FROM A REMOTE
`UNIT USING A SPREADING CHANNEL CODE FROM ONE OF THE CODE GROUPS
`
`507
`
`ASSIGN AN AMOUNT OF LINK BANDWIDTH TO THE REMOTE UNIT BASED
`ON THE CODE GROUP OF THE SPREADING CHANNEL CODE USED
`
`509
`
`END
`
`FIG. 5
`
`

`

`US 8,009,637 B2
`
`1
`METHOD AND APPARATUS FOR
`SPREADING CHANNEL CODE SELECTION
`
`REFERENCE(S) TO RELATED APPLICATION(S)
`
`2
`Simplicity and clarity in both illustration and description
`are sought to effectively enable a person of skill in the art to
`make, use, and best practice the present invention in view of
`whatis already knownin the art. One of skill in the art will
`appreciate that various modifications and changes may be
`made to the specific embodiments described below without
`departing from the spirit and scope ofthe present invention.
`Thus, the specification and drawings are to be regarded as
`illustrative and exemplary rather than restrictive or all-en-
`compassing, and all such modifications to the specific
`embodiments described below are intended to be included
`within the scope ofthe present invention.
`
`DETAILED DESCRIPTION OF EMBODIMENTS
`
`Various embodiments are described which may serve to
`improve spreading channel codeselection in wireless tech-
`nologies that employ two-stage ranging. For example, some
`ofthe embodiments enable a numberof spreading codesto be
`reused at each network node, potentially increasing the num-
`ber of codes available to each remote unit and thereby reduc-
`ing the collision rate. Rather than simply selecting a spread-
`ing channel
`code randomly,
`remote units,
`in some
`embodiments, select a spreading channel code based on one
`or more considerations such as pilot signal strength, remote
`unit location, a remote unit mobility level, and a priority class
`associated with the remote unit. Depending on the embodi-
`ment, network nodes can partition the spreading codes into
`groupsand then assign link bandwidth to remote units based
`on the group associated with the code selected by that remote
`unit.
`
`The disclosed embodiments can be more fully understood
`with reference to FIGS. 1-5. FIGS. 1 and 2 depict a wireless
`communication system 100 in accordance with multiple
`embodiments of the present invention. At present, standards
`bodies such as OMA (Open Mobile Alliance), 3GPP (3rd
`Generation Partnership Project), 3GPP2 (rd Generation
`Partnership Project 2) and IEEE (Institute of Electrical and
`Electronics Engineers) 802 are developing standards specifi-
`cations for wireless telecommunications systems. (These
`groups may be contacted via http://www.openmobilealli-
`ance.com, http:/www.3gpp.org/, http:/Awww.3gpp2.com/
`and http://www.ieee802.org/, respectively.) Communication
`system 100 represents a system having an architecture in
`accordance with one or more of the 3GPP2 technologies,
`suitably modified to implementthe present invention. Alter-
`native embodiments of the present invention may be imple-
`mented in communication systems that employ other or addi-
`tional technologies such as, but notlimited to, those described
`in the 3GPP specifications and/or those described in the
`TEEE’s 802.xx specifications (e.g., 802.16).
`Communication system 100 is depicted in a very general-
`ized manner, shown to comprise network nodes 111 and 112,
`remote units 101-103, and network 130. Those skilled in the
`art will recognize that FIGS. 1 and 2 do not depictall of the
`network equipment necessary for system 100 to operate but
`only those system components andlogical entities particu-
`larly relevant to the description of embodiments herein. For
`example, depending on the embodiment, network 130 may
`represent an IP (internet protocol) networkor, in combination
`with network nodes 111 and 112, a radio access network
`(RAN) or access network (AN). Thus, depending on the
`embodiment, network nodes 111 and 112 may comprise base
`transceiver stations (BTSs), access points (APs), and/or
`higher order devices such as base stations (BSs) (which
`include BTSs and base site controllers (BSCs)) and WLAN
`(wireless local area network) stations (which include APs, AP
`
`10
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`
`
`The present application claims priority from provisional
`application, Ser. No. 60/781,527, entitled “METHOD AND
`APPARATUS FOR SPREADING CHANNEL CODE
`
`SELECTION,” filed Mar. 10, 2006, which is commonly
`ownedand incorporated herein by reference in its entirety.
`
`FIELD OF THE INVENTION
`
`The present invention relates generally to communications
`and, in particular,
`to spreading channel code selection in
`communication systems.
`
`BACKGROUNDOF THE INVENTION
`
`Currently, standards bodies such as 3GPP (3rd Generation
`Partnership Project) and 3GPP2 (3rd Generation Partnership
`Project 2) are developing standardsspecifications for wireless
`telecommunications systems. (These groups may be con-
`tacted via http://www.3gpp.org/ andhttp://www.3gpp2.com/,
`respectively.) In particular, proposals for new physical layer
`link descriptions are being developed and submitted for con-
`sideration. In general, wireless technologies that employ
`spreading and two-stage ranging rely on remote units to ran-
`domly select a spreading channel codetouse with theirinitial
`ranging signal. The limited numberof ranging codes and the
`frequency of collisions between units using the same code for
`access degrade the performance of user services (greater
`access delays, e.g.) and diminish user experience,particularly
`with time sensitive services such as push-to-talk. Accord-
`ingly, it would be desirable to have an improved method and
`apparatus for spreading channel codeselection applicable to
`these wireless technologies.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG.1 is a depiction of a wireless communication system
`in accordance with multiple embodiments of the present
`invention.
`
`FIG. 2 is a block diagram depiction of the wireless com-
`munication system of FIG. 1, in accordance with multiple
`embodiments of the present invention.
`FIG.3 is a logic flow diagram of functionality performed
`by anetwork in accordance with multiple embodimentsofthe
`present invention.
`FIG.4 is a logic flow diagram of functionality performed
`by a remote unit in accordance with multiple embodiments of
`the present invention.
`FIG.5 is a logic flow diagram of functionality performed
`by anetwork in accordance with multiple embodimentsofthe
`present invention.
`Specific embodiments of the present invention are dis-
`closed below with reference to FIGS. 1-5. Both the descrip-
`tion andthe illustrations have been drafted with the intentto
`enhance understanding. For example, the dimensions of some
`of the figure elements may be exaggerated relative to other
`elements, and well-known elements that are beneficial or
`even necessary to acommercially successful implementation
`may not be depictedso that a less obstructed and a more clear
`presentation of embodiments may be achieved. In addition,
`unless specifically indicated, the order and grouping ofsig-
`naling is not a limitation of other embodiments that may lie
`within the scope of the claims
`
`

`

`US 8,009,637 B2
`
`3
`controllers/switches, and/or WLAN switches); however,
`none of these devices are specifically shown in FIGS. 1 or 2.
`In FIG. 2, remote unit 101 and network node 111 are shown
`communicating via technology-dependent, wireless interface
`150. Remote units, or user equipment (UEs), may be thought
`of as mobile stations (MSs); however, remote units are not
`necessarily mobile nor able to move. In addition, remote
`unit/UE platforms are known to refer to a wide variety of
`consumer electronic platforms such as, but not limited to,
`mobile stations (MSs), access terminals (ATs),
`terminal
`equipment, mobile devices, gaming devices, personal com-
`puters, personal digital assistants (PDAs). In particular,
`remote unit 101 comprises processing unit 105, and trans-
`ceiver 107. Depending on the embodiment, remote unit 101
`may additionally comprise a keypad (not shown), a speaker
`(not shown), a microphone (not shown), and a display (not
`shown). Processing units, transceivers, keypads, speakers,
`microphones, and displays as used in UEsareall well-known
`in the art.
`
`In general, components such as transceivers, keypads,
`speakers, microphones, and displays are well-known. For
`example, processing units are known to comprise basic com-
`ponents suchas, but neither limited to nor necessarily requir-
`ing, microprocessors, microcontrollers, memory devices,
`application-specific integrated circuits (ASICs), and/or logic
`circuitry. Such components are typically adapted to imple-
`ment algorithms and/or protocols that have been expressed
`using high-level design languages or descriptions, expressed
`using computer instructions, expressed using signaling flow
`diagrams, and/or expressed using logic flow diagrams.
`Thus, given a high-level description, an algorithm,a logic
`flow, a messaging/signaling flow, and/or a protocol specitica-
`tion, those skilled in the art are aware of the many design and
`developmenttechniques available to implementa processing
`unit that performsthe given logic. Therefore, remote unit 101
`represents a known device that has been adapted, in accor-
`dance with the description herein, to implement multiple
`embodiments of the present invention.
`Furthermore, those skilled in the art will recognize that
`aspects of the present invention may be implemented in and
`across various physical components and noneare necessarily
`limited to single platform implementations. For example, the
`network aspects may be implementedin or across one or more
`networkdevices, suchas in network node 111 or across one or
`more network nodes and/or network 130.
`Operation of embodiments in accordance with the present
`invention occurs substantially as follows. Processing unit 105
`of remote unit 101 receives signaling from network node 111
`via wireless interface 150 and transceiver 107. In most
`
`embodiments, the received signaling is pilot information con-
`veyed via a pilot channel of network node 111. In wireless
`technologies that employ spreading and two-stage ranging,
`prior art remote units randomly select a spreading channel
`code to use with their initial ranging signal. In contrast, pro-
`cessing unit 105 of remote unit 101 selects a spreading chan-
`nel code based on one or more considerations, depending on
`the particular embodiment. These considerations include the
`signal strength of the received signaling, the current location
`of the remote unit, the current mobility level of the remote
`unit, and/or the current priority class associated with the
`remote unit. Having selected a spreading channel code,pro-
`cessing unit 105 then transmits,via transceiver 107 and wire-
`less interface 150, an initial access signal using the spreading
`channelcode selected. This initial access signal may take the
`form of a ranging signal, for example, or other technology-
`dependent signaling required access the network node.
`
`20
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`4
`What type of spreading channel codes are selected and
`used also varies from one technologyto the next. The spread-
`ing channel codes may be orthogonal or quasi-orthogonal,
`although they need notbe either, such as the spreading codes
`specified in IEEE 802.16e. As another example, the spreading
`channel codes may be based on Chu sequencesas described in
`USS. Provisional Application 60/759,697, filed Jan. 17, 2006,
`entitled “PREAMBLE SEQUENCING FOR RANDOM
`ACCESS CHANNEL IN A COMMUNICATION SYS-
`
`TEM,”and hereby incorporated by reference.
`In some embodiments, network node 111 partitions the
`spreading channel codes that it makes available to remote
`units into code groups and transmits an indication of both the
`spreading channel codesavailable for use and the code group
`with which each is associated. This is information may be
`broadcast and received by remote unit 101 via a pilot channel
`ofnetwork node 111. Obviously,there are a great many ways
`to indicate the spreading channel codes andtheir associated
`code groups to remote units. The specific formatofthis sig-
`naling will, of course, depend upon how much information
`the remote units already have regarding the nature and iden-
`tity ofthe code set used system-wide andusedby the particu-
`lar network nodeitself.
`
`Thus, remote unit 101 receives signaling that indicates
`which spreading channel codes may be used by the remote
`unit for accessing network node 111 and the associated
`groupings of the codes. In these embodiments, then, process-
`ing unit 105 determinesa particular code group from whichto
`select a spreading channel code to use. Depending on the
`embodiment, remote unit 101 may determine a particular
`code group based on one or more considerations such as a
`received signal strength (the pilot signal strength, e.g.) from
`network node 111, the current location ofremote unit 101, the
`current mobility level of remote unit 101, and/or a current
`priority class associated with remote unit 101.
`This determination may be guided by the remote unit char-
`acteristics that individual code groups are intendedtotarget.
`For example, one code group maybe targeted for remote units
`that are associated with a particularpriority class, i.e. a par-
`ticular level of service. This could allow codes to be “set
`
`aside” for users who have purchased a premium level service
`or users who are involved in responding to emergencies, for
`example.
`Code groups could also be targeted for remote units in a
`particular area. For example, a code group might target
`remote units inside (or outside) region 125 around network
`node 111. Or a code group maytarget an area of particular
`interest such as that around a stadium, convention center,
`highway, shopping center, auditor1um, conference room,etc.
`Code groups could also target remote units having a particular
`level of mobility. For example, one code group maytarget
`low-mobility units while another targets high-mobility units.
`Another characteristic that individual code groups may be
`intendedto target is remote unit received signal strength, this
`being of signaling from the network nodesuchaspilot sig-
`naling that is received by the remote unit. (Signal strength is
`used throughout this description to generically refer to the
`various forms of signal measurementthat are used such as
`signal quality measurements, measurements for CQI (chan-
`nel quality indicator), and/or unique metrics derived from
`various combinations of both). One example of code groups
`targeting remote unit received signal strength would be for
`network node 111 to target one code groupfor units that have
`a received signal strength above a particular threshold and
`another code group for units that have a received signal
`strength below the particular threshold.
`
`

`

`US 8,009,637 B2
`
`5
`In effect, then, network node 111 could target one code
`group for coverage region 125 (roughly) and anotherfor the
`remainder of coverage area 121. (Note that a similar effect
`could be achieved using remote unit location, as described
`above.) Partitioning the spreading channel codes into code
`groups that are targeted for particular coverage regions can
`enable greater code reuse than is believed available today. For
`example, the spreading channel codes of one or more code
`groups targeting wireless coverage region 125, for instance,
`can be reused by network nodes with wireless coverage areas
`adjacent to network node 111. Thus, since interferenceis not
`a problem between coverage regions 125 and 126, network
`nodes 111 and 112 can reuse the spreading channel codes
`targeted forthese regions. Potentially, then, for a subset ofthe
`spreading channel codes a 1:1 reuse pattern could be used.
`Additionally or alternatively, network node 111 may moni-
`tor a system loadinglevel and partition the spreading channel
`codes into code groups based on the current system load. For
`example, network node 111 maypartition the spreading chan-
`nel codes into more code groups when the system loading
`level is greater than a loading threshold. Examples of system
`loadinglevel indicators that may be used include the number
`of collisions per code/code group, the number of transmis-
`sions per code/code group (equivalently utilization of codes/
`code groups), recent changes in the numberof users attached
`to the cell in different cell groups (predicting/anticipating a
`significant change in pattern), etc. The benefit sought by
`considering the level of system loadingis that by partitioning
`more code groups and having the remote unit selecting the
`appropriate code group, the system can save capacity by using
`information from the remote unit indicating how large a
`resource assignmentit needs. In other words, ifthere are only
`two groups, then the network will still end up doinga fair bit
`of over assignment of resources for mobiles which are very
`close to the network node, as the network may think that they
`are as far away as halfway out within the cell. However, by
`partitioning 10 different groups, then the network can know
`that the user who is very near the tower is within the closest
`Yoor so ofthe cell/sector and thus can use an even smaller
`assignment. The downside of breaking the codes into more
`groupsis that of potentially creating more collisions within
`one group while another group is under-utilized. However,
`this can be addressed by dividing the unit among code groups
`in different time intervals.
`Thus, depending on the embodiment, remote unit 101 may
`determine a particular code group based on one or more
`considerations such as a received signal strength from net-
`work node 111, the current location of remote unit 101, the
`current mobility level of remote unit 101, and/or a current
`priority class associated with remote unit 101. As discussed
`above, this determination may be guided by the remote unit
`characteristics that individual code groups are intended to
`target. Network node 111 may also indicate to remote unit
`101, in addition to the codes and the code groupings, what
`characteristics the code groups are intendedtotarget.
`Using this received information or some pre-defined infor-
`mation regarding the targeted characteristics of the code
`groups, remote unit 101 determines a particular code group
`from which to select a spreading channel code. In some
`embodiments, processing unit 105 simply selects a spreading
`channel code randomly from the spreading channel codes
`associated with the determined group. Thus, the selection of
`a spreading channel code based on various considerations
`may be performed bydetermining a code group, based on the
`particular considerations, and then selecting, perhaps ran-
`domly, a spreading channel code from the determined code
`group.
`
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`A numberof examples of remote unit characteristics for
`which code groups could be targeted was provided above.
`Thus, remote unit 101 considers the applicable characteristics
`or combination of characteristics that the available code
`
`groups target to determine a code group from whichto select
`acode. For example, remote unit 101 may determineto select
`from one code group because of the remote unit’s current
`location (per GPS, e.g.) or because the user has purchased a
`premiumservice level. In another embodiment, remote unit
`101 may determine to select from a particular code group
`because the pilot signal strength of network node 111 is
`greater than a threshold and because remote unit 101 cur-
`rently has a low level ofmobility. Another code group may be
`determinedfor selection in the casethat either the pilot signal
`strength is below the threshold or if remote unit 101 has a
`mobility level above a mobility threshold. This is just one
`example ofthe many possible combinations ofcharacteristics
`that code groups might target to effect a partitioning of the
`spreading codes.
`Depending on the embodiment, however, remote units may
`not be locked into selecting a spreading channel code from the
`code group targeted by the applicable remote unit character-
`istics. For example, remote unit 101 may determine the code
`groupthat appliesto its currentsituation, select a code to use
`from that code group, and then determine that the code
`selected is being used by another device. In such a case,
`remote unit 101 mayselect another code from the determined
`code group or may select a code from another code group
`altogether.
`Some other embodiment-specific aspects that may be
`incorporated into the embodiments already described follow.
`The spreading channel codesthatare partitioned into groups,
`while unique as codes, may share a common modulation and
`coding type. Thus, when a remote unit, in this case, selects a
`spreading channel code,it is not selecting a level of redun-
`dancyor a type of modulation/datarate.
`In addition to selecting a spreading channel code, in some
`embodiments the remote unit will select the spreading chan-
`nel code and a timeperiod for using the spreading channel
`code. In other words, the remote unit selects a code-time
`combination (e.g., a code and a start time) from a group of
`code-time combinations. Thus, the available code-time com-
`binations are partitioned into groups just as the codes alone
`would be, except that the same codes may be in different
`groups but associated with different time periods for use.
`Determination of a group of code-time combinations from
`which to select could occur as described herein for code
`groups.
`After network node 111 receives an initial access signal
`from remote unit 101 using the spreading channel code
`selected by remote unit 101, network node 111 mayassign an
`amountof link bandwidth (forward and/orreverse link band-
`width) to the remote unit based on the code group of the
`spreading channel code used. For example, ina case in which
`the code group has beentargeted for a level of signal strength
`ofa signal received by the remote unit greater than a threshold
`and the remote unit uses a spreading channel code from that
`code group, the network node may assign a smaller amount of
`link bandwidth to the remote unit than would be otherwise
`
`assigned. Here, the network node may assumethat the smaller
`amountoflink bandwidth will be sufficient since the remote
`
`unit has signal strength greater than the threshold, as indi-
`cated by the spreading channel code the remote unit used.
`Potentially then, using this technique, less bandwidth may be
`usedin certain situations, improving system capacity.
`FIG.3 is a logic flow diagram of functionality performed
`by anetwork in accordance with multiple embodimentsofthe
`
`

`

`US 8,009,637 B2
`
`8
`designed for execution on a computer system. This sequence
`ofinstructions may include, but is not limitedto, a subroutine,
`a function, a procedure, an object method, an object imple-
`mentation, an executable application, an applet, a servlet, a
`sharedlibrary/dynamic loadlibrary, a source code, an object
`code and/or an assemblycode.
`Whatis claimed is:
`
`7
`present invention. Logic flow 300 begins (301) with the net-
`work partitioning (303) a plurality of spreading channel
`codesinto a plurality of code groups. The network then trans-
`mits (305) signaling that indicates the code groupings pro-
`ducedbythe partitioning and receivesan initial access signal
`from a remote unit using a spreading channel code from a
`code group ofthe plurality of code groups. Logic flow 300
`1. A method for spreading channel code selection, the
`then ends (309).
`method comprising:
`FIG.4 is a logic flow diagram of functionality performed
`receiving by a remote unit signaling from a network node
`by a remote unit in accordance with multiple embodiments of
`that indicates groupings of the spreading channel codes
`the present invention. Logic flow 400 begins (401) when a
`that the remote unit may use for accessing the network
`remote unit receives (403) signaling from a network node.
`node;
`The remote unit selects (405) a spreading channel code based
`selecting by the remote unit a spreading channel code from
`on at least one characteristic from a group of a signal strength
`a determined groupof the indicated groupings, wherein
`ofthe received signaling, a current location ofthe remote unit,
`the determined group is determined based onat least one
`a current mobility level of the remote unit, and a current
`characteristic from a group of: a signal strength of the
`priority class associated with the remote unit. The remote unit
`received signaling and a current location of the remote
`then transmits (407) an initial access signal using the spread-
`unit; and
`ing channel code. Logic flow 400 then ends (409).
`transmitting by the remote unit an initial access signal
`FIG.5 is a logic flow diagram of functionality performed
`using the spreading channel code.
`by anetwork in accordance with multiple embodimentsofthe
`2. The method of claim 1 wherein the initial access signal
`present invention. Logic flow 500 begins (501) with the net-
`comprises a ranging signal.
`work partitioning (503) a plurality of spreading channel
`3. The method of claim 1 wherein receiving by the remote
`codes into a plurality of code groups. The network then
`unit signaling from the network node comprises receiving by
`receives (505) an initial access signal from a remote unit
`the remote unit signaling via a pilot channel of the network
`using a spreading channel code from a code group ofthe
`node.
`plurality of code groups. In response, the network assigns
`4. The method of claim 1 wherein selecting by the remote
`(507) an amountoflink bandwidth to the remote unit based on
`unit the spreading channel code from the determined group
`the code group of the spreading channel code used by the
`comprises randomly selecting by the remote unit the spread-
`remote unit. Logic flow 500 then ends (509).
`ing channel code from the determined group.
`Benefits, other advantages, and solutions to problems have
`5. The method of claim 1 wherein a common modulation
`been described above with regard to specific embodiments of
`and coding type is associated with each of the indicated
`the present invention. However, the benefits, advantages,
`groupings of spreading channel codes.
`solutions to problems, and any element(s) that may cause or
`6. The method of claim 1 further comprising:
`result in such benefits, advantages, or solutions, or cause such
`benefits, advantages, or solutions to become more pro-
`whenthe remote unit determines that the spreading chan-
`
`nounced are not to be construed asacritical, required, or nel code selected is being used by another device, select-
`essential feature or elementof anyorall the claims.
`ing by the remote unit a spreading channel code from a
`As used herein and in the appendedclaims, the term “com-
`group of the indicated groupings other than the deter-
`prises,” “comprising,” or any other variation thereof is
`mined group.
`7. The method of claim 1:
`intended to refer to a non-exclusive inclusion, such that a
`process, method, article of manufacture, or apparatus that
`comprises a list of elements does not i