9.1.18 Immediate assignment

3GPP44.018GSM/EDGE Radio Resource Control (RRC) protocolMobile radio interface Layer 3 specificationRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

This message is sent on the CCCH or encapsulated in the PACKET CS COMMAND message on the PACCH (see 3GPP TS 44.060) by the network to the mobile station in idle mode to change the channel configuration to a dedicated configuration while staying in the same cell or to the mobile station in packet idle mode to change the channel configuration to either an uplink or a downlink packet data channel configuration, or to provide the configuration of an MBMS session in the cell. In addition, this message is sent on the CCCH to a mobile station in packet idle mode when it has sent an EGPRS MULTILATERATION REQUEST message indicating ‘RLC Data Block method’ or ‘Page Response for Positioning Event’ (see table 9.1.18.1) or indicating ‘Access Burst method’ or ‘Extended Access Burst method’ (see sub-clause 3.5.2.1.2, sub-clause 3.11 and table 9.1.18.1a).

The L2 pseudo length of this message is the sum of lengths of all information elements present in the message except the IA Rest Octets and L2 Pseudo Length information elements.

Message type: IMMEDIATE ASSIGNMENT

Significance: dual

Direction: network to mobile station

Table 9.1.18.1: IMMEDIATE ASSIGNMENT message content

IEI	Information element	Type / Reference	Presence	Format	length
	L2 Pseudo Length	L2 Pseudo Length 10.5.2.19	M	V	1
	RR management Protocol Discriminator	Protocol Discriminator 10.2	M	V	1/2
	Skip Indicator	Skip Indicator 10.3.1	M	V	1/2
	Immediate Assignment Message Type	Message Type 10.4	M	V	1
	Page Mode	Page Mode 10.5.2.26	M	V	1/2
	Dedicated mode or TBF	Dedicated mode or TBF 10.5.2.25b	M	V	1/2
	Channel Description	Channel Description 10.5.2.5	C	V	3
	Packet Channel Description	Packet Channel Description 10.5.2.25a	C	V	3
	Request Reference	Request Reference 10.5.2.30	M	V	3
	Timing Advance	Timing Advance 10.5.2.40	M	V	1
	Mobile Allocation	Mobile Allocation 10.5.2.21	M	LV	1-9
7C	Starting Time	Starting Time 10.5.2.38	O	TV	3
	IA Rest Octets	IA Rest Octets 10.5.2.16	M	V	0-11
6D	Extended TSC Set	Extended TSC Set 10.5.2.82	O	TV	2

Table 9.1.18.1a: IMMEDIATE ASSIGNMENT message content (MTA Access Burst or Extended Access Burst Method only)

IEI	Information element	Type / Reference	Presence	Format	length
	L2 Pseudo Length	L2 Pseudo Length 10.5.2.19	M	V	1
	RR management Protocol Discriminator	Protocol Discriminator 10.2	M	V	1/2
	Skip Indicator	Skip Indicator 10.3.1	M	V	1/2
	Immediate Assignment Message Type	Message Type 10.4	M	V	1
	Page Mode	Page Mode 10.5.2.26	M	V	1/2
	Dedicated mode or TBF	Dedicated mode or TBF 10.5.2.25b	M	V	1/2
	Request Reference	Request Reference 10.5.2.30	M	V	3
	Timing Advance	Timing Advance 10.5.2.40	M	V	1
	Mobile Allocation	Mobile Allocation 10.5.2.21	M	LV	1-9
	IA Rest Octets	IA Rest Octets 10.5.2.16	M	V	0-11
05	Request Reference 1	Request Reference Alt 10.5.2.87	O	TV	5
06	Request Reference 2	Request Reference Alt 10.5.2.87	O	TV	5
07	Request Reference 3	Request Reference Alt 10.5.2.87	O	TV	5
08	Request Reference 4	Request Reference Alt 10.5.2.87	O	TV	5

9.1.18.0a Dedicated mode or TBF

A mobile station not supporting GPRS may ignore the contents of this information element and regard it as an unnecessary IE. Such mobile station shall assume that this message assigns a dedicated mode resource.

If the Dedicated mode or TBF IE indicates that neither a TBF nor a dedicated resource has been assigned (see sub-clause 10.5.2.25b) then the IA Rest Octets IE shall be coded using the ‘LL’ option and indicate either a ‘0’ or a ‘1’ for the Compressed_Inter_RAT_HO_INFO_IND field (see sub-clause 10.5.2.16). In this case a mobile station that has enabled PEO and has sent an EGPRS MULTILATERATION REQUEST message indicating ‘Access Burst’ or ‘Extended Access Burst’ method (see sub-clause 3.5.2.1.2 and sub-clause 3.11) shall ignore the Compressed_Inter_RAT_HO_INFO_IND field and examine the Request Reference 1, Request Reference 2, Request Reference 3, and Request Reference 4 information elements (as necessary) in attempt to find an Immediate Assignment message (see Table 9.1.18.1a) that matches its transmitted EGPRS MULTILATERATION REQUEST message (see sub-clause 10.5.2.87). A mobile station that has enabled PEO and has sent an EGPRS MULTILATERATION REQUEST message indicating ‘RLC Data Block method’ or ‘Page Response for Positioning Event’ shall ignore an Immediate Assignment message where the Dedicated mode or TBF IE indicates neither a TBF nor a dedicated resource has been assigned.

9.1.18.0b Channel Description

If the Dedicated mode or TBF IE indicates that the message assigns a dedicated mode resource, the mobile station shall consider this information element present in the message.

9.1.18.0c Packet Channel Description

If the Dedicated mode or TBF IE indicates that the message assigns a Temporary Block Flow (TBF), the mobile station shall consider this information element present in the message. If the Dedicated mode or TBF IE indicates that this message is the first of two in a two-message assignment of an uplink or downlink TBF, the mobile station shall ignore the contents of this information element and regard it as an unnecessary IE.

9.1.18.0d Request Reference

If this message is used in an assignment of a downlink TBF, the network shall code this information element, e.g. by using a suitably offset frame number, such that the resource reference cannot be confused with any CHANNEL REQUEST message sent by a mobile station.

If the IA Rest Octets IE indicates that this message is the second message of a two-message assignment of an uplink or downlink TBF, this information element shall have the same contents as the first message of the assignment.

When set to the value ‘0111 1111’, the RA information of the Request Reference IE indicates that an Extended RA field may be included in the IA Rest Octets. The mobile station shall use the information in the Extended RA field to identify the Immediate Assignment message corresponding to an EGPRS Packet Channel Request message. If the Extended RA field is not included, the mobile station shall assume that the Immediate Assignment message does not correspond to the EGPRS Packet Channel Request message.

A mobile station has enabled PEO and has sent an EGPRS MULTILATERATION REQUEST message indicating ‘Access Burst’ method or ‘Extended Access Burst’ method (see sub-clause 3.5.2.1.2 and sub-clause 3.11) shall ignore this field and instead examine the Request Reference 1, Request Reference 2, Request Reference 3 and Request Reference 4 information elements (as necessary) in attempt to find an IMMEDIATE ASSIGNMENT message (see Table 9.1.18.1a) that matches its transmitted message (see sub-clause 10.5.2.87).

When the mobile station receives the IMMEDIATE ASSIGNMENT message encapsulated in the PACKET CS COMMAND message on the PACCH (see 3GPP TS 44.060), it shall ignore the contents of this information element and regard it as an unnecessary IE.

9.1.18.0e Timing Advance

If the IA Rest Octets IE indicates that this message is the second message of a two-message assignment of an uplink or downlink TBF, the mobile station shall ignore the contents of this information element and regard it as an unnecessary IE.

9.1.18.1 Mobile Allocation

If this message assigns a dedicated mode resource and the Channel Description IE does not indicate frequency hopping, the length indicator of this information element shall be set to zero, and the mobile station shall consider the IE as an unnecessary IE.

If this message assigns a TBF and the Packet Channel Description IE does not indicate frequency hopping or if it uses indirect encoding of a hopping RF channel configuration, the length indicator of this information element shall be set to zero, and the mobile station shall consider the IE as an unnecessary IE.

9.1.18.2 Starting Time

This information element appears if e.g. a frequency change is in progress.

If this message is used in an assignment of an uplink or downlink TBF, the mobile station shall ignore the contents of the Starting Time information element if included and consider it as an unnecessary IE.

9.1.18.3 IA Rest Octets (Frequency parameters, before time)

The sum of the length of this IE and the L2 Pseudo Length of the message equals 22.

If the starting time IE is present but not the frequency parameters, before time construction, the mobile stations must wait until the starting time before accessing the channel.

If the starting time IE is present and the Channel Description IE does not indicate frequency hopping the mobile station shall consider the frequency parameters, before time construction as unnecessary in the message and the mobile must wait until the starting time before accessing the channel.

If the starting time IE is not present, the mobile station shall consider the frequency parameters, before time construction as unnecessary in the message.

9.1.18.4 IA Rest Octets (assignment of uplink or downlink TBF)

If the Dedicated mode or TBF IE indicates that this message is used in an assignment of a TBF, this information element shall contain a Packet Uplink Assignment, Packet Downlink Assignment, Second Part Packet Assignment construction or Multiple Blocks Packet Downlink Assignment construction.

If the Dedicated mode or TBF IE indicates that this message assigns a dedicated mode resource, but not that the mobile station is identified in the IA Rest Octets IE information element, the mobile station shall consider the Packet Uplink Assignment, Packet Downlink Assignment, Second Part Packet Assignment and Multiple Blocks Packet Downlink Assignment constructions as unnecessary in the message.

9.1.18.5 Extended TSC Set

If the message is sent on the PACCH to a mobile station that indicates support for extended TSC sets (see 3GPP TS 24.008 [79]) this information element may be included to provide TSC related information for the assigned radio resources. In the absence of this information element the TSC related information provided by the Channel Description IE and Packet Channel Description IE shall apply.

9.1.18.6 Request Reference N

A mobile station that has enabled PEO and has sent an EGPRS MULTILATERATION REQUEST message indicating the ‘Access Burst’ method or ‘Extended Access Burst’ method shall ignore the Request Reference information element and shall instead examine the Request Reference 1, Request Reference 2, Request Reference 3 and Request Reference 4 information elements (as necessary) in attempt to find an IMMEDIATE ASSIGNMENT message (see Table 9.1.18.1a) that matches its transmitted EGPRS MULTILATERATION REQUEST message (see sub-clause 10.5.2.30 and sub-clause 10.5.2.87).

A mobile station that has enabled PEO and has sent an EGPRS MULTILATERATION REQUEST message indicating the ‘RLC Data Block’ method or ‘Page Response for Positioning Event’ shall only examine the Request information element in attempt to find an IMMEDIATE ASSIGNMENT message (see Table 9.1.18.1a) that matches its transmitted EGPRS MULTILATERATION REQUEST message (i.e. it shall ignore all instances of the Request Reference N information element if included).