§
§ Both CS Fallback (CSFB) and VoLGA rely on the existing circuit voice network, but
§
§ This was originally adopted for Wi-Fi/
§
§ A technological approach for delivering voice and SMS services over LTE access networks
§ Leverages a mobile operator’s existing core voice network
§ Derived from the existing 3GPP GAN standard
§ A technological approach for delivering voice and SMS services over LTE access networks
§ Leverages a mobile operator’s existing core voice network
§
§
§
§ The VoLGA Access Network Controller (VANC) , as a GAN gateway between LTE and CS domain, securely connects a subscriber to the infrastructure of a network operator and voice calls and other circuit switched services such as SMS are then securely transported between the mobile device and the Gateway.
§
2). UMA/GAN OV
§ 3GPP Generic Access Network (GAN) specifications add Wi-Fi as an access technology to 3GPP based networks such as GSM and UMTS.
§ GAN requires a new dual mode mobile devices which have both a GSM/UMTS radio interface and a Wi-Fi radio interface.
§ The concept is to connect the already existing Mobile Switching Centers to the LTE network via a gateway.
§ As no fallback to a legacy network is required, call setup times are not increased and the user's quality of experience is consistent with that of the
§ The GAN specification was extended in Release
3). Full service transparency
§ Supports all circuit services over LTE
§ Supports IMS RCS and combinational services (CS+IMS) over LTE
§ Supports handover of active calls between LTE and GSM/UMTS
§ Supports expected LTE femtocell deployments
Pros:
§ Voice and Data over LTE
§ Call setup times as good as
§ Preserves CS core investments
§ External controller (VANC) minimizes impact to core network - No MSC upgrades
§ Supports simultaneous voice/ data over LTE
§
§ Delivering voice over LTE validates LTE QoS capabilities
§ Voice services delivered natively through LTE femtocell
§ The VoLGA forum decided to use the SRVCC as the means to handover
§ No VoLGA specific features required in the MSC or SGSN for VoLGA is a great plus for deployment in a running network.
Cons:
§ Not 3GPP standardized yet -
§ Not fully standardized yet as the stage 3 specification has not yet been finalized
§ Limited operator support
§ GAN-based dual-mode mobile phones is required
§ SRVCC-capable mobile is required
§ Only T-Mobile strongly enthusiastic right now
§ Scaling and Roaming
§ Limited LTE Coverage if only hotspots at the initial phase
§ It also requires changes to handsets, as well as a mechanism for allowing the network to trigger LTE-to
§ http://docs.google.com/View?id=ddh56dhg_295htd3pzcn
§
§
§
§ On the network side,
§ On the mobile device side, the protocol stack initially developed for GAN can also be re-used in large parts. The two main software additions required are to include the LTE access technology as a radio bearer together with a modified handover procedure
§ All other network elements and the interfaces between them already exist and are reused without any modifications.
§ A-interface is used to connect the VANC to a GSM MSC (
§ The Iu-interface is used to connect the VANC to the UMTS MSC.
§ No changes are required on these network nodes to support voice, SMS and other services over the LTE network.
§ SGi: SGi is defined in TS 23.401. It is the reference point between the P-GW and the packet data network. The
§ Sv: Sv is defined in TS 23.216, where it is defined as the reference point between the MME/SGSN and MSC Server. In this specification, Sv applies to two interfaces:
(1) between the MME and HOSF, and
(2) between the HOSF and MSC Server.
HOSF = Handover Selection Function
§ Z1 (UE – VANC): Z1 is the reference point between the UE and VANC, which is based on the Up interface defined in TS 43.318.
§ Z3 (VANC – HOSF): Z3 is the reference point between the VANC and HOSF. It is based on GTPv2-C as specified in TS 29.274. The Z3 reference point is used for the creation and deletion of VANC-UE bindings in the HOSF, and to route the SRVCC PS to CS Handover Request message to the VANC.
§
§ The user gets the exact same set of services and user experience when on all three networks (GSM,
§ Given that the CS system cannot handle LTE ECGI, VoLGA shall support a mapping / translation function between GERAN Cell ID or UTRAN Service Area ID and LTE ECGI (E-UTRAN Cell Global Identifier).
7-1). VANC discovery support functions
§ For
§ The DNS server shall be accessed in the same PDN as the VANC.
§ The PDN GW shall support the DHCP server function including VANC discovery specific options.
§ The UE shall interact with DNS and DHCP services for the purpose of VANC discovery by means of the PDN connection after this has been established by means of the PDN GW.
7-2). Support CS Services:
The
§ The following set of CS domain voice, supplementary and value-adding services and business principles (e.g. for roaming and interconnect) shall be made available over the evolved PS access.
§ MO/MT voice calls
§ Emergency calls
§ Video telephony
§ Supplementary Services
§ CAMEL services
§ SMS
§ USSD
§ TTY
§ Customised Alerting Tones
§ Circuit Switched Data
§ G3 Fax
7-3). Handover for
§ The VoLGA forum decided to use the SRVCC as the means to handover
§ A very important functionality of
§ For
7-4). VoLGA Function – Roaming:
§
§ International Roaming: Local Breakout - preferred for
§ International Roaming: Home Network Routing - It is possible to use an APN that establishes a connection to the P-GW in the home network of the subscriber.
§
§
§
§ Location information shall be provided for emergency calls.
§ If the VANC has detected that the UE is attempting to establish an emergency call, it shall – as part of the PCC interaction – indicate to the PCRF that the bearer is needed for an emergency call.
8-1). VoLGA Function Entity – VANC:
§ The only new network element introduced is the VoLGA Access Network Controller (VANC) , as a gateway between LTE and CS domain.
§ In a
§ The
§ VANC manages the UE’s connection to the
§ The VANC behaves like a BSC (VoLGA A-mode) or RNC (
§ The VANC shall support CS handover functions towards the MSC in the same way as a BSC/RNC.
§ The VANC shall be able to interact with a 3GPP PCRF for the control of the
§ Translation between the UE-VANC protocol and BSSAP/RANAP.
§ Handover preparation and execution in cooperation with the HOSF,
§ Supports the UE-VANC protocol
§ The AAA Server authenticates the UE using EAP-AKA when the UE initiates the establishment of a secure tunnel to the SeGW in VANC.
§ GAN-style IKEv2 authentication and tunnel mode IPSec is used between the UE and the SeGW function of the VANC
§ Performs UE security binding verification
§ Supports the detection of emergency call being setup.
§ Supports location function (i.e. behaves like a GMLC) to acquire location information from the MME.
§ The load distribution between VANCs within the same VANC pool is required
§ This controller scales up as traffic increases.
§ HOSF = Handover Selection Function
§ In case of handover, the HOSF decides if the HO request from the MME is for
§ HOSF shall support the VANC-UE binding creation and deletion procedures so that it can make these decisions based on the stored record of the serving VANC for the UE.
§ HOSF is a logical functional entity, which can be deployed according to operator's requirements (e.g. separate entity, embedded in MME or VANC).
§ On the (LTE) phone, the ‘dialer’ sends and receives the exact same messages it would over GSM or
§
§ The mobile devices side it is also likely that
§ The major change in the UE software is handover handling, as the network based Single Radio Voice Call Continuity (SRVCC) feature will be used.
§ Discovery of and registration with VANC.
§ CS related NAS procedures for MM and CM through VANC.
§ VoIP on the user plane per IETF RFC 4867.
§ Ensures UE-VANC control plane communication is secure
§ The VoLGA forum decided to use the SRVCC as the means to handover
§ No VoLGA specific features are required in the MSC or SGSN for VoLGA
§ SRVCC from E‑UTRAN access to 3GPP UTRAN/GERAN CS accesses for voice calls that are anchored in the IMS, and handling of SRVCC from 3GPP UTRAN/GERAN CS accesses to E‑UTRAN/UTRAN (HSPA) direction is not specified in the release (R8)
§ The impact from
§ EPS needs to support Policy Control and Charging (PCC)
§ Support of appropriate QoS for the
§ EPS must support handover with the CS network, e.g. similar to SRVCC
§ LTE must offer support for Header Compression on the user plane (RoHC)
EPS: E-UTRAN
§ The functionality for E-UTRAN is specified in TS 36.300.
§ No additional functionality is required of the E-UTRAN to support
§ In addition, E-UTRAN needs to provide support for SRVCC as specified in TS 23.216.
EPS: MME
§ The functionality for MME is specified in TS 23.40.
§ In addition, MME needs to provide support for SRVCC as specified in TS 23.216.
§ No additional functionality is required of MME to support
EPS: S-GW and P-GW
§ The functionality of S-GW and P-GW are specified in TS 23.401 for GTP based S5/S8 and TS 23.402 for PMIP based S5/S8.
§ No additional functionality is required of the S-GW and P-GW to support
CS entities
§ VoLGA does not require any enhancement in existing CS elements like MSC but for
§ There shall be no impact of
§
CS: MSC Server
§ The functionality of the MSC Server is specified in TS 23.216.
§ The MSC Server is not used for
CS: MSC/VLR
§ The functionality of the MSC/VLR is specified in existing 3GPP specifications.
§ No additional functionality is required of the MSC/VLR to support
CS: PCRF
§ The functionality of the PCRF is specified in TS 23.203.
§ PCRF is optional and is only deployed if the operator supports PCC.
§ No additional functionality is required of the PCRF to support
§
§
§ VANC discovery control - It shall be possible to configure the UE with: APN (in HPLMN or VPLMN), List of VPLMN
§ Voice mode control - It shall be possible to configure the UE with a list of modes to support voice service. For each mode it shall be possible to configure: priority or operator policy
§ Security configuration - The UE shall be configurable with parameters necessary to enable the proper use of IPsec between the UE and the VANC to secure the Z1 interface.
What is a GSM Gateway
回覆刪除GSM gateways provide a way to route traffic from a
GSM network to another type of network.
GSM gateways are often used to route traffic from wireless
GSM networks to wired networks. By routing traffic through a
GSM gateway, the wireless network can be reduced in size and complexity.
The routing between public networks can also be reduced by routing traffic
through a GSM gateway. A GSM gateway is a device that connects a
GSM network to a different type of network.