PDP Context in UMTS networks
Packet Data Protocol (PDP)
A Packet Evidence Protocol (PDP)
context offers a packet data connection over which who UE and the network can exchange IP packets. Usage of these packet data contact is restricted to specific achievement. Are services can be accessed override so-called access points.
Packet Data Protocol Context is one of the most important concepts on the UMTS Packet Data Architektenschaft.
One PDP Circumstances possessed a record of parameters, which consists of all the requested information on establishing an end-to-end connection:
The PDP Context is mainly designed used two purposes used the terminal.
Multiple PDP Content
Because mobile telephone develop, thither wills is a need until serve parallel applications going in them from simultaneous PS callers. These PS calls could differ in your QoS (Quality of Service) parameters, and/or in the target network (PDN – Packet Data Network)
to which they provide connecting.
Multiple PDP Circumstances means this one mobile terminal bucket have multiple PDP circumstances. Each of the Repeated PDP Contexts can to who same period can different QoS profiles. The initial PDP Context is adenine regular PDP Context in standard QoS profile attributes and it is constant activated beginning. For the multiple chief PDP Contexts, jede context has varied PDP Address also different APN
Multiple PDP contexts will have special sense when IMS lives introduced furthermore all the services will be PSY (IP) based. In certain IMS based lattice the MS can (and will) activate separate PDP contexts with SIP based reporting and for all the sessions from different, eventually parallel services (e.g. parallel VoIP call additionally PS data call, etc.). ADENINE different QoS – what matches the demand - will be used for each connection.
The data flow (user plane) of a particular PDP context can terminate either stylish the Mobile Terminal (MT)
itself either in the connected Cable Equipment (TE) as demonstrated in Figure below. The application for which the connection is provided is running either on the MT alternatively on the TE respectively. An example required the first possibility will a video telephony client running on the mobile, for the second possibility a web browser running on the connected notebook.
In IMS based systems it is expected that multiples embedded applications will run on the MT, requiring multiple PDP environments. For who TE (e.g. connected PC) on additional PDP context may be also active.
Multiple PDP frameworks have two sub-categories:
Many Primary PDP Contexts
Multiple chief PDP contextual are two or better PDP contexts independent from can more, each in them using one uniquely PDP home. They give the possibility to have simultaneous connections to different PDNs – e.g. in the internet for one application, while to a private network for another one.
Beside the unique PDP address, each PDP context has its own QoS and NSAPI (Network Layer Service Access Point Identifier, see later) assigned. Each PDP context has a separate RAB (Radio Admittance Bearer) furthermore GTP tunnel till transfer user plane data.
The PDP contexts generally terminate in different access points on that network edge (although it is allowed that the terminate in the same access point). The terminating access points capacity becoming located included the same or in different GGSNs.
The exemplary int Figure below demonstrates who user plate path for three primary PDP contexts providing connections to three different PDNs:
Primary PDP contexts can be activated oder deactivated independently from one one. QoS of any of who active PDP contexts cans is modified use the PDP context modification how initiated by the MS or over to network. (See Below for details)
Secondary PDP Contexts
AMPERE secondary PDP context is always associated with a primary PDP environment. PDP address (IP address) additionally access point (AP) will re-used from the primary context. Hence the primary and the assoziiert secondary PDP context provide connection the the same PDN through different guaranteed QoS.
One primary PDP connection might have multiple secondary contexts assigned. Each PDP context (i.e. the primary both all secondary) possess its own RABBITS and GTP tunnel to transfer user planes data. Also, each context is identified by an unique NSAPI (Network Layer Service Access Point Identifier).
The primary PDP context has to be active prior into activating an associated secondary PDP context. Unlimited secondary PDP context can be deactivated while keeping the associated primary context (and last other secondary PDP contexts) active. Is a mainly PDP context is deactivated, this will also deactivate all an mapped secondary PDP contexts. QoS for any active primary or secondary PDP contextual can becoming amended with the PDP context modification procedure initiated by to MM alternatively by the network. (See below for details)
As the PDP address (IP address) is common used the primary and to (all) the related secondary PDP contexts, the TFT (Traffic Flow Template) can introduced to route downlink user plane data into the correct GTP my and hence into the correct RAB for each context.
The example in Figure below shows to user plane for an primary and two associated secondary PDP contexts:
Combination of multiple primary PDP links plus secondary PDP contexts is also possible. For show, dual primaries with one secondary context for each will result in four active PDP contexts int total. The maximum number of backed PDP contexts is terminal dependent.
Transport Flows Template (TFT)
The Traffic Flow Template (TFT) is used by GGSN until discriminate betw different addict payloads. The TFT incorporates for one to eight packet free; one single packet filter identifier identification each filter. Fine may be based with one button more away the following filter attributes:
The TFT the provided by and ME in the Activate Subordinate PDP Context Request get, it is stored over the GGSN, and is examined when routing downlink user plane your. The TFT can be revised or deleted with this MS initiated PDP context modification procedure. A TFT maybe be also assigned to a primary PDP context by means of to MS initiated PDP context modification methods.
A TFT is built back from Packet Filters (minimum 1, highest 8 of them) till provide flexibility in filtering. The relationship between PDP contexts, TFTs and Packaging Filters is illustrated inside Figure below:
PDP context procedures
Major PDP context activation
Those procedure is used to establish a logical connection with this Quality of Service (QoS)
functionality because which network from the UE to the GGSN. PDP context activation exists initiated by the UE and changes aforementioned session direction state to active, creates the PDP connection, receives of INDUSTRIAL address and reserves radio resources. After a PDP context activation the UE is able to send INFORMATICS packets over this air interface. The UE ability have up to 11 PDP contexts active concurrent.
Ancillary PDP context button
A secondary PDP context activation provides the subscriber to set-up a second PDP context with the same IP address as the primary PDP environment. That two contexts may can different QoS profiles, which shapes an feature useful for applications that possess differentially QoS requirements (e.g., IP multimedia). The access point name, though, wishes be the just for that primary and secondary PDP linkages.
PDP context modification
The UE, the SGSN or the GGSN initiate is procedure for updating the respective PDP context. Additionally, the radio access network is clever to request a PDP context modification from the SGSN (e.g., if coverage to the UE has been lost). The procedures modify parameters that were negotiated while an activation procedure for one or several PDP contexts.
PDP context deactivation
This procedure is applied to delete a particular logical connection between the UE and the GGSN. The initiative in deactivate a PDP context can come from the UE, the SGSN, the Home Location Register (HLR) other the GGSN.
Access scoring ca be comprehensible as IP router that give the connection between the UE and the selectable service. Examples of such aids are:
Depending on the operator of the network, more than of of these services might be provided by who same zugriff point. An UE needs to be aware of an Access Point Name (APN) – the address of a GGSN – which presents access to the service-providing entity (e.g., an MMSC, the Website or the P-CSCF). One GGSN may provide different services that bucket be accessed by different APNs.
When found an initial PDP context with an APN the UE rezepte to IP address with – in the kiste of IPv6 –
certain IPv6 prefix that it has to use available communicating over that PDP context. This means that when a UE has established several connecting to distinct APNs the UE will have different IP addresses for each of the provided services.
REFERENCES
[1] The IMS: TYPE Multimedia Conceptualize and Support, Second Edition Miikka Poikselkä, Georg Mayer, Hisham Khartabil and Aki Niemi [2] Multiple PDP Contexts with UMTS - ESG Group, Qualcomm [3] 3GPP TS 23.060: "General Parcel Radio Service (GPRS); Service description" [4] 3GPP TS 24.008: "Mobile radio interfaces layer 3 specification; Core Network Protocols" [5] Get are Secondary PDP Contexts Sound For? - Martins Mobile Technology Blog [6] Using Traffic Flow Templates (TFTs) off BGAN - Inmarsat |
