Wi3GTalk: Fixed-mobile convergence

Transcription

1 Wi3GTalk: Fixed-mobile convergence 1. Introduction Freecoms has developed a solution for fixed-mobile convergence. The basic feature of the solution is the seamless (with no call interruption and no intervention by the end user) handover form a Wifi VoIP call to a UMTS VoIP call. As described in par. 4, this solution opens a set of opportunities to approach new customers with an innovative VoIP offer, covering both fixed and mobile service at the same time. The solution allows MVNOs to price aggressively the new converged fixed and mobile service and gain market share (and fixed market traffic) in a consolidating and price eroding market. The marketing message to MVNOs could be: change the rules of the game to survive. Our belief is that a MVNOs can no longer ignore the potential of VoIP technology and have to pursue it in an innovative and aggressive way. 2. Solution architecture Wi3GTalk is a client /server solution to be used in a VoIP standard environment, based on SIP protocol. It leverages on the recent increase of Wifi access points and integrates it with UMTS network. Wi3GTalk is composed of a SW Client and a SW Server. It requires a dual mode Wifi + UMTS mobile phone, with a data UMTS SIM. An end user can initiate a call in a Wifi hot spot, keep talking while walking out of the hot spot, without loosing the call. Wi3GTalk handles automatically the handover between the Wifi and the UMTS data network. 2.1 Server side The SW Server (Handover Server) (HS) must be installed as a boarder element between big and the servers of a standard SIP architecture. In this position HS fully behaves like a typical Session Border Controller. HS opens a communication based on on VoIP standard protocols (SIP and RTP) with all 1/8

2 other standard servers of a typical VoIP architecture (Sip Proxy Server, Call Controller, Media Gateway etc.) HS manages a connection with SIP clients, with full support in case of handover between UMTS and Wifi network. PSTN UAC UAC Handover Server Media Gateway SIP Proxy Server Call Controller LAN Fig.1: Server architecture 2.2 Client side The SW Client (Handover Client) (HC) is installed on mobile terminals with dual mode UMTS and Wifi connectivity. A standard SIP client (softphone), chosen by the users, is also installed on the terminal. HC manages a communication with the softphone, base on standard VoIP protocols SIP and RTP, and manages also the connection with the HS and the transport switching between UMTS and Wifi network. This switching is initiated and timely concluded in the case the Wifi signal level is detected by HC to be below a predefined level. 2/8

3 SoftPhone SIP Based (es. XTEN XPRO) (( )) (( )) UMTS Wi-Fi SIP/RTP Wi4Talk Client Device UMTS/Wi-Fi (es. HTC - Universal) Fig.2: Client architecture The following fig.3 shows the complete architecture of the solution and explain the two possible routes that a the VoIP call can take: through Wifi or through UMTS, according to the strength of respective signals. It is important to underline that in the case of UMTS, a data only SIM card is necessary: the call is a VoIP message: it uses the IP channel and not the UMTS voice channel. So applicable tariff is typically a flat access plan: even in the case of a pay per Kbytes plan, the cost of the call is very low, since data exchange in a VoIP call is negligible. The value of our solution can be : Full seamless mobility: a call is not interrupted if the terminal crosses from a UMTS cell to a Wifi cell and vice versa Very low cost per call: data plan only (not voice) required on the SIM Fixed mobile integration: the same device acts as a fixed VoIP and as a mobile VoIP, without any intervention from the users. 3/8

4 PSTN Copertura Wi-FI SS7 Enterprise Terminali Dual-Mode con SIP SoftPhone e Wi4Talk Client LAN SIP Proxy Server Call Controller Media Gateway Router Firewall LAN Backbone UMTS Wi4Talk Server Copertura Rete UMTS Operatore Pubblico GGSN Copertura Wi-FI IP IP Terminali Dual-Mode con SIP SoftPhone e Wi4Talk Client LAN IP Router Firewall Enterprise Fig.3: Solution Architecture 3. SW description In this paragraph a more detailed description on the two SW components is presented. 3.1 Handover Server The Server is written in Java and compiled for a Linux platform. HS works on two public IP address. It is composed by 4 modules: the modules which are necessary for the operation are indicated as core, the other as opt : 1. Media Proxy (core) : this module performs the audio streams management, it is based on MjSip, a Sip stack with GNU licence 4/8

5 2. MediaGW Box (core): this module manages the instances of the Media Proxy, to be created or destroyed when there is a change in the interfaces on the client side after a handover event 3. Handover Stack SIP+ (core): this module manages standard SIP signalling, and handover signalling. It has been designed starting from MjSip by adding proprietary methods, which are necessary to control handover 4. SIP Server/Registrar (opt): it is a standard SPS/Registrar. It can substitute an external SIP server. It is useful in a testing environment. db SPS / Registrar Client IP Address 1 (SX) SIP RTP SIP Proxy HandOver stack SIP+ SIP IP Address2 (DX) RTP MGW Box Media Proxy HandOver Server Fig.4: Handover server functional diagram 3.2 Wi3GTalk Client The client is written in embedded C and C++, compiled for Windows Mobile and LiMo (Linux Mobile). The Symbian version is under development in a Java environment. Wi3GTalk Client must be installed on dual mode terminals (UMTS/Wifi), it receives on the loopback address ( ) the SIP and RTP signals from the softphone and generates the handover signals to the HS, according to quality and field intensity of the UMTS and Wifi radio signals. It is made of six modules: 5/8

6 1. Media Proxy (core): this is the module for the management of audio streams (two-way UMTS stream and two-way Wifi stream in each call), it is based on Resiprocate, a SIP stack with GNU licence. 2. MediaGW Box (core): this module manages the instances of Media Proxy module 3. Handover Stack SIP+ (core): this module manages the standard SIP signals and the handover proprietary signals. It has been designed to by extending the SIP standard stack (GNU Resiprocate licence) with proprietary methods necessary to control the handover. 4. Auth. EAP-AKA (opt): this module extracts from the SIM card the necessary credentials to authenticate users (IMSI code) 5. Netprobe: this module interacts with the radio levels of the terminal and delivers to the Client the information about intensity and quality of UMTS and Wifi signals. This is a key feature that allows the terminal to decide if and when to switch from one mode to the other (Wifi or UMTS) 6. GUI: this is the graphical interface to configure the setting of the terminal (i.e. server IP address, setting of preferential network, signal level to trigger the handover, setting of manual or automatic handover, ). It also presents on the device screen some information about the networks and call current status. 6/8

7 Server IP Address 1 Server IP Address 2 (( )) (( )) SoftPhone SIP (Es. XTEN XPRO) UMTS :5060 Netprobe.dll SIP Proxy HandOver stack SIP+ Wi-Fi SIP RTP MGW Box Media Proxy :10000:10015 Wi4Talk Client Fig.5: Wi3GTalk Client functional diagram 4. Application Scenarios a) General MVNO: Wi3GTalk can play the role of a very innovative service extension tool for a MVNO. It requires a simple data only SIM, with a low cost plan (either flat or per kb) and opens to the end users a set of interesting possibilities: - access to cheap VoIP communication in Wifi covered areas (private and public) - access to cheap VoIP communication in UMTS covered areas - seamless handover between the two connection This would allow the MVNO to extend its offer to home fixed line substitution, by an aggressive marketing action: installing a Wifi connection at home will allow to use the mobile phone in fully convergent way, with no need for a traditional fixed voice plan from the incumbent. 7/8

8 b) MVNO in Distribution Sector: The same move can be proposed in this case with the addition of a free Wifi connection inside the commercial areas. The end user in the commercial areas can make free VoIP calls and this will increase the service and the hospitality of the areas. This can be part of a broader marketing plan aim to transform the customer perception of a commercial area. c) Tier 2 mobile operators: Wi3GTalk can attract second tier mobile operators that have to differentiate themselves from incumbent. By proposing the Wifi VoIP solution at home they can enter the market of home broadband internet access and offset the fixed incumbent operator. On the UMTS side, they may keep a defensive pricing (close to current UMTS voice price/minute) in order not to erode their existing mobile revenues. A second solution, that requires a customization of the mobile terminals and allows to switch a call from Wifi VoIP to a standard UMTS voice call, is under development. d) Very Large Companies: Wi3GTalk can significantly reduce the telecommunication costs in large organizations that could act as closed MVNO for their employees. It is enough to install and run Wi3GTalk in the Company Data Centre and acquire data only SIM form a UMTS operator. 5. Conclusions Freecoms has a wide and long term experience in fixed voice, broadband and VoIP both in terms of technology development and in terms of operation management in Italy and elsewhere. Wi3GTalk came out from Freecoms R&D, with the support of a specialized Italian University. The solution has the capabilities to change the perception of difference between a fixed and a mobile communication. It can also severely reduce the end user price of both fixed and mobile communication, if properly presented and positioned by new and innovative MVNOs. 8/8