(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2012/0202478 A1
`
` Van Lieshout et al. (43) Pub. Date: Aug. 9, 2012
`
`
`US 20120202478Al
`
`(54) METHOD AND APPARATUS FOR
`CONFIGURING RADIO ACCESS
`FUNCTIONALITY OF A WIRELESS
`COMMUNICATION UNIT
`
`(30)
`
`Foreign Application Priority Data
`
`Oct. 5, 2009
`
`(GB) ................................... 09173949
`
`Publication Classification
`
`(75)
`
`Inventors:
`
`Gert-Jan Van Lieshout, Apeldoorn
`(NL) Himke Van Der Velde
`Zwolle (NL)
`
`’
`
`(73) Assignee:
`
`SAMSUNG ELECTRONICS CO.
`LTD., Suwon-si, Gyeonggi-do (KR)
`
`(51)
`
`Int' 0'
`H04W 36/14
`H04W 80/00
`
`(2009.01)
`(2009.01)
`
`(52) US. Cl. ........................................................ 455/419
`
`(21) Appl. No.:
`
`13/500,528
`
`(57)
`
`ABSTRACT
`
`(22) PCT Filed:
`
`Oct. 1, 2010
`
`A method for configuring radio access functionality of a
`wireless communication unit within a wireless communica-
`
`(86) PCT No.:
`
`PCT/KR2010/006718
`
`§ 371 (c)(1)S
`(2), (4) Date:
`
`Apr. 5, 2012
`
`tion network, the method comprising sending to the wireless
`communication unit an indication of a required radio access
`protocol version to which the wireless communication unit is
`to be reconfigured.
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`

`

`Patent Application Publication
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`Aug. 9, 2012 Sheet 1 of 15
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`US 2012/0202478 Al
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`US 2012/0202478 A1
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`Aug. 9, 2012 Sheet 4 of 15
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`Patent Application Publication
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`Aug. 9, 2012 Sheet 6 of 15
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`US 2012/0202478 A1
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`Patent Application Publication
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`US 2012/0202478 A1
`
`Aug. 9, 2012
`
`METHOD AND APPARATUS FOR
`CONFIGURING RADIO ACCESS
`FUNCTIONALITY OF A WIRELESS
`COMMUNICATION UNIT
`
`TECHNICAL FIELD
`
`[0001] The field of this invention relates to a method and
`apparatus for configuring radio access functionality of a wire-
`less communication unit. The invention is applicable to, but
`not limited to, a method for configuring radio access func-
`tionality of a wireless communication within a 3rd Genera-
`tion Partnership Project (3GPP) evolved universal terrestrial
`radio access network, a network entity, a wireless communi-
`cation unit and a wireless communication network therefor.
`
`BACKGROUND ART
`
`In the field of cellular communication systems, for
`[0002]
`example cellular communication systems conforming to 3rd
`Generation Partnership Project (3GPP) specifications, typi-
`cally the network controls the mobility of a mobile commu-
`nication unit (or user equipment (UE) in 3GPP parlance) that
`is in a connected mode (or to be precise in 3GPP terms in an
`RRC_CONNECTED state). For example,
`the network
`decides with which cell the UE maintains a radio connection
`
`(also referred to as the serving cell). The network applies the
`handover procedure to move the UE from one cell, namely the
`serving cell, to another cell, referred to as the target cell. The
`network decides the cell, as well as the Radio Access Tech-
`nology (RAT) in some circumstance, that the UE should
`connect to typically based on radio quality. However, the
`network may also take into account other factors, such as cell
`load, UE capabilities, the type of bearers that are (being)
`established, etc. To assist the handover decision process, the
`network normally configures the UE to perform measure-
`ments on a serving frequency for its current serving cell
`(referred to as intra-frequency measurements), on other fre-
`quencies used by the Radio Access Technology for that net-
`work (referred to as inter-frequency measurements) and/or on
`frequencies used by other Radio Access Technologies (re-
`ferred to as inter-RAT measurements).
`[0003]
`FIG. 1 illustrates an example of a typical overall
`handover procedure 100 for a UE 105. More specifically FIG.
`1 illustrates an Intra-MME (Mobility Management Entity)/
`Serving Gateway handover as defined in the 3GPP Technical
`Specification (TS) 36.300.
`[0004] Once a decision has been made to perform a han-
`dover, the handover procedure 100 starts with a preparation
`stage 110 comprising a source eNB 102 (enhanced NodeB)
`forwarding a HANDOVER REQUEST message 112, as
`defined in 3GPP TS 36.413, to a target eNB 104, the HAN-
`DOVER REQUEST message 112 comprising handover
`preparation information needed to prepare for the handover.
`The HANDOVER REQUEST message 112 carries the han-
`dover preparation information within a HandoverPrepara-
`tionInformation message, defined in 3GPP TS 36.331, and
`includes:
`
`radio access capabilities for the UE;
`[0005]
`a current radio access (e.g. access stratum, AS)
`[0006]
`configuration;
`[0007] RRM (Radio Resource Management) configura-
`tion, such as information kept only by the eNB that is
`used primarily for Radio Resource Management (where
`
`usage of such RRM configuration information is eNB
`implementation-dependent); and
`[0008]
`radio access (AS) context, i.e. information kept
`only by the eNB (i.e. information that is not exchanged
`across the radio interface), such as information needed
`to perform RRC (Radio Resource Control) connection
`re-establishment.
`
`it
`If the target eNB 104 accepts the handover,
`[0009]
`reserves the radio resources and decides on the details of the
`
`radio access configuration to be used by the UE 105 in the
`target cell. This radio access configuration is returned to the
`source eNB 102 within a HANDOVER REQUEST ACK
`message 114, as defined in 3GPP TS 36.413. This HAN-
`DOVER REQUEST ACK message 114 carries the radio
`access configuration within a HandoverCommand message,
`that is defined in 3GPP TS 36.331. The HandoverCommand
`
`message again carries an RRCConnectionReconfiguration
`message, as defined in 3GPP TS 36.331. When used to per-
`form a handover within, say, E-UTRA, this message includes
`the radio access configuration to be used in the target cell,
`such as:
`
`the measurement configuration, expressed by
`[0010]
`way of a ‘delta’ compared to the configuration used in
`the source cell
`(the delta indicating configuration
`changes, as opposed to complete configuration informa-
`tion, in order to reduce the size of the message);
`[0011]
`the mobility control information, which specifies
`the target cell identity (by means of a cell identity) and
`some characteristics (such as a frequency, a bandwidth
`and additional spectrum emission information; only if
`different from what is used in the source cell, i.e. delta
`signaling information is provided), the new radio access
`identity to be used in the target cell, the cell-specific
`radio resource configuration (common for all UEs),
`dedicated resources used for initial access in the target
`cell and a timer to limit the duration that the UE tries
`
`connecting to the target cell;
`[0012]
`the UE-specific radio resource configuration (i.e.
`the dedicated radio configuration), also expressed as a
`delta, compared to the configuration used in the source
`cell; and
`[0013]
`the security configuration, i.e. the algorithms, if
`different from the ones used in the source cell (delta), as
`well as parameters affecting the derivation of radio
`access security keys (i.e. an indication whether a new
`base key is to be used and a counter that is incremented
`upon every handover).
`[0014] After the preparation stage 110, handover execution
`is performed as illustrated generally at 120, whereby the
`source eNB 102 proceeds with the handover, which includes
`the source eNB 102 transparently forwarding a RRCConnec-
`tionReconfiguration message 122 to the UE 105 (i.e. it does
`not change the message contents; the source eNB does how-
`ever perform integrity protection and ciphering of the mes-
`sage), and the UE 105 attempting to connect to the target cell
`(steps 124, 126), and returning a RRCConnectionReconfigu-
`rationComplete message 128, as defined in 3GPP TS 36.331.
`[0015] The signaling used upon handover, as defined in
`3GPP TS 36.331 to a large extent applies delta signaling for
`the various parameters, or fields in 3GPP parlance, whereby
`the radio access network (Evolved Universal Terrestrial
`Radio Access Network? EUTRAN in the case of 3GPP TS
`
`36.331) only signals values that change from those used in the
`source cell. 3GPP TS 36.331 specifies the signaling (the
`
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`Protocol Data Unit content) by means of ASN.1. Fields for
`which delta signaling applies are defined as optional, so they
`may be absent, in combination with a need code of ‘ON’
`whereby in case of absence the receiver takes no action with
`respect to such fields, and where applicable continues to use
`the existing value (and/or associated functionality). FIG. 2
`illustrates an example 200 of a message definition for RRC-
`ConnectionReconfiguration messages in accordance with
`3GPP TS 36.331. For the example illustrated in FIG. 2, the
`field measConfig 210 is defined as being OPTIONAL (at
`220), with a need code of ‘ON’ (at 230). It shouldbe noted that
`whilst the example illustrated in FIG. 2 only shows the fields
`present at the message level, similar considerations with
`regard to fields being defined as ‘optional’ with need codes of
`‘ON’ apply at other levels. For example, FIG. 3 illustrates an
`example 300 of a definition for a RadioResourceConfigDedi-
`cated information element (IE) (in accordance with 3GPP TS
`36.331) comprising several optional fields with need codes
`set to ‘ON’.
`
`[0016] Whilst the use of delta signaling in this manner
`enables a significant reduction in the signaling overhead
`required when a handover is performed, it also creates issues
`with respect to backward compatibility when a target eNB is
`arranged to support an earlier release of the radio access
`protocols than a version supported by both the serving eNB
`and UE.
`
`For optional fields with a need code of ‘ON’,
`[0017]
`explicit signaling is required to deactivate functionality asso-
`ciated with that field, such as for backward compatibility
`purposes, as applies when the target eNB does support the
`concerned functionality. For example, in the case where, say,
`the sps-Config field 310 illustrated in FIG. 3 is absent in a
`RadioResourceConfigDedicated identity element (IE), the
`UE will continue to use previously configured values.
`Accordingly, in order to deactivate previously active func-
`tionality, it is necessary to include the appropriate fields in a
`manner that is suitable to ‘clear’ the previously configured
`values.
`
`[0018] The RRC protocol defined in 3GPP TS 36.331
`includes different kinds of protocol extensions that may be
`added for later versions of the specifications, of which there
`are two prime categories: non-critical extensions (NCE) and
`critical extensions (CE). It has been agreed that the non-
`critical extension mechanism is
`the primary extension
`mechanism, since it just adds on to the existing signaling.
`This, for example, means that when a message is received that
`includes non-critical extensions that are not comprehended
`by the receiver, the message may be processed as if the exten-
`sions were not present. In contrast, a message that includes
`critical extensions that are not comprehended is completely
`ignored by the receiver. Such critical and non-critical exten-
`sions are provided in various different manners:
`[0019]
`defining new message types;
`[0020]
`defining a new message version;
`[0021]
`adding an optional open SEQUENCE at the end
`of a message or within a size-delimited container e.g. a
`bit string;
`[0022]
`extending the values of a field of ENUMER-
`ATED type by using a value previously defined as spare
`or by adding a new value after an extension marker;
`[0023]
`extending the values of a field of CHOICE type
`by using a value previously defined as spare or by adding
`a new value after an extension marker;
`
`extending a field of SEQUENCE type by adding
`[0024]
`new fields after an extension marker;
`[0025]
`etc.
`
`DISCLOSURE OF INVENTION
`
`Technical Problem
`
`[0026] Currently there is no defined way for a target eNB to
`deactivate radio access configuration functions that are intro-
`duced in a protocol version not supported by the target eNB.
`If the UE continues using the concerned functions, severe
`interoperability problems are likely to occur.
`[0027] Thus, a need exists for an improved mechanism for
`configuring radio access functionality of a wireless commu-
`nication unit.
`
`Solution to Problem
`
`[0028] Accordingly, the invention seeks to mitigate, allevi-
`ate or eliminate one or more of the above mentioned disad-
`
`vantages singly or in any combination. Aspects of the inven-
`tion provide a network entity, a wireless communication unit,
`a wireless communication network, and a method therefor as
`described in the appended claims.
`[0029] According to a first aspect of the invention, there is
`provided a method for configuring radio access functionality
`of a wireless communication unit within a wireless commu-
`
`nication network, the method comprising, at a radio access
`network entity, sending to the wireless communication unit
`an indication of a required radio access protocol version to
`which the wireless communication unit is to be reconfigured.
`[0030] Thus, in one example embodiment of the invention,
`the network entity is able to (re)configure radio access func-
`tionality that is active within the wireless communication unit
`in accordance with a required radio access protocol version.
`For example, the network entity is able to configure the wire-
`less communication unit to deactivate radio access function-
`
`ality introduced in later versions of the radio access protocol,
`relative to that version supported by the network entity (the
`required version), even though the network entity does not
`recognise such functionality.
`[0031] According to an optional feature of the invention,
`the method comprises receiving from a source network entity
`a handover request for a wireless communication unit; and
`sending to the wireless communication unit an indication of a
`target radio access protocol version to which the wireless
`communication unit is to be configured. In this manner, the
`network entity is able to configure the wireless communica-
`tion unit to deactivate radio access functionality introduced in
`later versions ofthe radio access protocol relative to the target
`version supported by that network entity (the required ver-
`sion), even though the network entity does not recognise such
`functionality.
`[0032] According to an optional feature of the invention,
`the method further comprises determining, upon receipt of a
`handover request, at least one of a source network entity radio
`access protocol version and a wireless communication unit
`radio access protocol version, and if the at least one deter-
`mined source network entity and wireless communication
`unit radio access protocol version comprises a version later
`than a supported radio access protocol version, sending to the
`wireless communication unit an indication of a target radio
`access protocol version to which the wireless communication
`unit is to be configured. For example, the method may com-
`prise, upon receipt of a handover request, determining a
`
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`
`source network entity radio access protocol version and a
`wireless communication unit radio access protocol version,
`and ifthe source network entity radio access protocol version
`and the wireless communication unit radio access protocol
`version comprise versions later than the supported radio
`access protocol version, sending to the wireless communica-
`tion unit an indication of a target radio access protocol version
`to which the wireless communication unit is to be configured.
`In this manner, the wireless communication unit may only be
`sent an indication of a required radio access protocol version
`to which it is to be reconfigured when it is determined that a
`source network entity radio access protocol version and/or a
`wireless communication unit radio access protocol version is
`a later version than that supported by the target network
`entity, potentially avoiding unnecessary reconfiguration of
`the radio access functionality of the wireless communication
`unit.
`
`[0033] According to an optional feature of the invention,
`the step of determining at least one of a source network entity
`radio access protocol version and a wireless communication
`unit radio access protocol may comprise reading a field
`within a received HANDOVER REQUEST message. The
`field is arranged to comprise an indication of at least one of a
`supported radio access protocol version for a source network
`entity from which the handover request was received; a sup-
`ported radio access protocol version for the wireless commu-
`nication unit; and a latest radio access protocol version in
`which active functionality of the wireless communication
`unit is introduced.
`
`[0034] According to an optional feature of the invention,
`the field within the received HANDOVER REQUEST mes-
`sage may form a part of a HandoverPreparationlnformation
`message contained within the HANDOVER REQUEST mes-
`sage.
`
`[0035] According to an optional feature of the invention,
`determining a source network entity radio access protocol
`version may comprise looking up, within Operation and
`Maintenance (0&M) configuration information, a supported
`radio access protocol version for a source network entity from
`which the handover request was received.
`[0036] According to an optional feature of the invention,
`the target radio access protocol version ofwhich an indication
`is sent to the wireless communication unit may comprise a
`latest supported radio access protocol version.
`[0037] According to an optional feature of the invention,
`the target radio access protocol version ofwhich an indication
`is sent to the wireless communication unit may comprise a
`latest supported radio access protocol version from a subset of
`radio access protocol versions.
`[0038] According to an optional feature of the invention,
`sending to the wireless communication unit an indication of a
`target radio access protocol version to which the wireless
`communication unit is to be configured may comprise adding
`the indication ofthe target radio access protocol within a field
`of a connection reconfiguration message to be contained
`within a HANDOVER REQUEST ACK message returned to
`the source network entity.
`[0039] According to an optional feature of the invention,
`sending to the wireless communication unit an indication of a
`target radio access protocol version to which the wireless
`communication unit is to be configured may comprise adding
`the indication ofthe target radio access protocol within a field
`of a connection re-establishment message to be sent to the
`
`wireless communication unit in response to receiving a con-
`nection reestablishment request message from the wireless
`communication unit.
`
`[0040] According to an optional feature of the invention,
`the method may comprise receiving an indication of a
`required change to a radio access protocol version for which
`the wireless communication unit is configured to comply with
`and sending to the wireless communication unit an indication
`of a required radio access protocol version to which the wire-
`less communication unit is to switch to.
`
`[0041] According to an optional feature of the invention,
`the wireless communication network may comprise an
`evolved universal terrestrial radio access network (E-UT-
`RAN).
`[0042] According to a second aspect of the invention, there
`is provided a computer program product comprising execut-
`able program code for configuring radio access functionality
`of a wireless communication unit within a wireless commu-
`
`nication network, the executable program code operable for
`sending to the wireless communication unit an indication of a
`required radio access protocol version to which the wireless
`communication unit is to be reconfigured.
`[0043] According to a third aspect of the invention, there is
`provided a network entity for supporting radio access to a
`wireless communication network, the network entity com-
`prising a signal processing module arranged to send to the
`wireless communication unit an indication ofa required radio
`access protocol version to which the wireless communication
`unit is to be reconfigured.
`[0044] According to a fourth aspect ofthe invention there is
`provided a method for configuring radio access functionality
`of a wireless communication unit within a wireless commu-
`
`nication network, the method comprising sending to a target
`network entity a handover request for a wireless communi-
`cation unit, the handover request comprising an indication of
`at least one of a source network entity radio access protocol
`version and a wireless communication unit radio access pro-
`tocol version.
`
`[0045] According to a fifth aspect of the invention there is
`provided a computer program product comprising executable
`program code for configuring radio access functionality of a
`wireless communication unit within a wireless communica-
`
`tion network, executable program code operable for sending
`to a target network entity a handover request for a wireless
`communication unit, the handover request comprising an
`indication of at least one of a source network entity radio
`access protocol version and a wireless communication unit
`radio access protocol version.
`[0046] According to a sixth aspect of the invention there is
`provided a network entity for supporting radio access to a
`wireless communication network, the network entity com-
`prising a signal processing module arranged to send to a target
`network entity a handover request for a wireless communi-
`cation unit, the handover request comprising an indication of
`at least one of a source network entity radio access protocol
`version and a wireless communication unit radio access pro-
`tocol version.
`
`[0047] According to a seventh aspect of the invention there
`is provided a method for configuring radio access function-
`ality of a wireless communication unit within a wireless com-
`munication network, the method comprising, at the wireless
`communication unit, receiving an indication of a required
`radio access protocol version to which the wireless commu-
`nication unit is to be reconfigured, and deactivating radio
`
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`
`access functionality introduced in radio access protocol ver-
`sions later than the indicated required radio access protocol
`version.
`
`[0048] According to an eighth aspect of the invention there
`is provided a computer program product comprising execut-
`able program code for configuring radio access functionality
`of a wireless communication unit within a wireless commu-
`
`nication network, the executable program code operable for
`receiving an indication of a required radio access protocol
`version to which the wireless communication unit is to be
`
`reconfigured, and deactivating radio access functionality
`introduced in radio access protocol versions later than the
`indicated required radio access protocol version.
`[0049] According to a ninth aspect of the invention there is
`provided a wireless communication unit for connecting to a
`wireless communication network, the wireless communica-
`tion unit comprising a signal processing module arranged to
`receive an indication of a required radio access protocol ver-
`sion to which the wireless communication unit is to be recon-
`
`figured, and deactivate radio access functionality introduced
`in radio access protocol versions later than the indicated
`required radio access protocol version.
`[0050] According to a tenth aspect of the invention there is
`provided a wireless communication network comprising a
`network entity for supporting radio access to the wireless
`communication network, the network entity comprising a
`signal processing module arranged to send to the wireless
`communication unit an indication of a required radio access
`protocol version to which the wireless communication unit is
`to be reconfigured.
`[0051] These and other aspects of the invention will be
`apparent from, and elucidated with reference to, the example
`embodiments described hereinafter.
`
`ADVANTAGEOUS EFFECTS OF INVENTION
`
`[0052] The present invention advantageously provides at
`least some of the following benefits over possible solutions
`currently available:
`[0053]
`(i) additional handover delay introduced through the
`source eNB deactivating functionality introduced in later pro-
`tocol versions that that supported by the target eNB is sub-
`stantially avoided;
`[0054]
`(ii) the target eNB is able to cause the UE to deac-
`tivate unsupported functionality without the need for the tar-
`get eNB to explicitly signal deactivation of such functional-
`ity;
`(iii) the need for all fields to always be included
`[0055]
`within signaling for functionality that is required to b contin-
`ued following handover (as would be required if all function-
`ality defined using optional fields with need code set to OR),
`and the associated signaling overhead,
`is substantially
`avoided; and
`[0056]
`(iv) the need to significantly extend a radio access
`protocol, such as to define multiple default values as would be
`required to support switching to default configurations, is
`substantially avoided.
`
`BRIEF DES