Framework for low cost voice communication using mobile devices

0001Framework for low cost voice communication using mobile devices

0002Field of the invention

0003The present invention relates to devices, methods and infrastructure for the communication of voice and audio signals over a wireless communication network. In particular, the invention relates to communication within a very-low bandwidth framework between two or more persons with mobile devices or to/from a mobile device.

0004Description of Related Art

0005In the present days there is a vast array of technologies at our disposal for communication. In the field of voice telephony this has expanded to encompass not only traditional fixed line telephony, but also mobile and internet based telephony. This expanding base of communications devices and techniques opens the way for new paradigms for the delivery of voice telephony services. Of particular interest are mobile and internet based voice communications, due to the potential for further reduction in the cost of services as well as expanding the range of available services.

0006Mobile telecommunications includes devices, infrastructure and algorithms for voice communication using a wireless infrastructure. In addition to standard voice communications modern mobile telephony networks also provide services for the transmission of text, multimedia and digital data. There is a myriad of standards including Global System for Mobile Adaptive Multi-Rate (GS -AMR) voice coder for the transmission of voice data. Short Message Service (SMS) and Multimedia Message Service (MMS) asynchronous store and forward text and multimedia messaging services and General Packet Radio Service (GPRS) for the transmission of packetised digital data. Third generation mobile services enable the expansion of services to include wideband telecommunications applications such as broadcast multimedia (EDGE and UMTS protocols).

0007Voice Over Internet Protocol (VoIP) services provide the possibility of voice transmission over the internet for personal computer users using a real-time transport protocol for the packetised data. This enables the transmission of voice conversations in addition to typical internet content such as pictures and HTML files. VoIP also enables multiple users to be connected to one another in a voice conversation. A major advantage of VoIP services is the ability to offer extremely economical voice communications by using proprietary low bandwidth methods for the transmission of the voice signal and also the fact the voice data is not treated any differently from normal internet traffic and as such, costs are independent of the distance between call participants and possibly even call duration. VoIP has the added advantage of allowing the simultaneous communication of other content such as pictures, video, text etc.

0008Summary of the invention

0009The present invention's objective is to provide a means for the efficient transmission of voice and audio between mobile devices and to/from mobile devices. The invention is divided into a number of key components to enable the delivery of this service, namely: • A method for encoding/decoding and representation of the voice/audio signal • A method for transmission of the voice/audio signal • An infrastructure for delivery of the communication service

0010These are detailed as follows in the remainder of this summary. The features of the invention will be apparent in the annotated drawings and descriptions of preferred embodiments that follow this brief description.

00111. A method for encoding, decoding and representation of the voice/audio signal

0012The signal, be it specifically voice or more generally audio, can be represented using many different approaches, each delivering varying degrees of quality, bandwidth, signal delay and computational demand. A major role of the invention is to interface voice communications originating from different types of source (be it conventional telephone, computer or mobile device), hence, supporting many of the existing standards and signal representations as well as providing propriety methods for signal representation in order to offer better services to the user.

0013Existing speech and audio signal coding standards have been mentioned in the section on existing art; hence, only possible extensions of the invention to proprietary signal coding techniques are discussed here. Such proprietary techniques may incorporate the technology discussed in the section on prior art. The invention includes an apparatus for the encoding and decoding the voice/audio signal by an application installed on the client device. The encoded signal is transmitted by the mobile device to other mobile devices, computer terminals or conventional telephones using the server infrastructure described in a following section.

0014An application used by mobile devices for the encoding and decoding of the proprietary signal representation used by the invention should have some or all of the following features: • Minimal bandwidth while meeting other design requirements for the application; • Acceptable signal delay (due to algorithmic and computational delay) for the given application; • The ability for users to set signal quality/bandwidth according to their requirements; • The ability for the application or service provider to set the bandwidth/quality according to network requirements; • Additional customization of the voice representation including the ability to alter the resulting voice reconstruction quality (including pitch, timbre etc.);

0015While the application is primarily targeted at providing connectivity for mobile devices within the invention's infrastructure, it is also feasible that such an application may also be made available to computing devices with fixed line connections to the internet.

00162. A method for transmission of the voice signal

0017Transmission of voice data is carried out within existing telecommunications infrastructure. The invention enables transmission using existing technology (conventional telephone and VoIP) and also using proprietaiy technology that is part of the invention described herein.

0018Devices using conventional telephony rely on the transmission means provided by the vendors of telephony services and are outside the domain the invention. An apparatus is required by the invention for relaying such transmissions by the server described in the following section.

0019Devices using the encoding/decoding application described in the previous section also require an apparatus for the transmission/reception of the voice data. Mobile devices using this application may carry out transmission over any available mobile data connection (such as GPRS, EDGE and UMTS) while devices with fixed data connections may use conventional internet connections (TCP/IP, VoIP over LAN, MODEM. WiFi etc). The key feature of voice transmission using the transmission apparatus described is that data is encoded using a packet specification defined within the invention and the transmission network protocol through which this is carried out just treats this as arbitrary data.

00203. An infrastructure for delivery of the communication service

0021The invention incorporates a client-server infrastructure for the delivery of communications services. A user may connect to a server by mobile device via data conneclion, by computer via the internet, or by conventional telephone. Depending on the mode of connection, the means and availability of services provided by the invention will vaiy. Servers are responsible for setting up connections between users and also provide management of user and system data.

0022The various functionalities of the invention can be divided into client and server side operations.

0023Client-side operations: • Connection to and disconnection from the server is normally initiated by the client. The client's connection status may be used by the server to notify other users of his/her connection status where a client may have the choice of a number of different 'on-line' or 'off-line^* states (for example, on-line states may include 'available for all voice calls', 'available for store and forward voice-messaging only' or 'busy'). All communications must be made via the server in order to resolve internet IP addresses and also for the management of usage statistics (for instance: billing, analysis of clients usage of the invention) The client device may be required to periodically update their connection status with the server, otherwise the connection will 'time out' and the user's status will become 'off-line'. The client device may be required to store messages before sending or while receiving in order to support multiple simultaneous voice messaging connections. Encoding and decoding of the voice/audio signal is conducted on the client side (although the server may facilitate a conversion between dissimilar encodings). This may include standard encoding methods as used by mobile devices and Voice-over-IP (VoIP) services as well as proprietary techniques used specifically by the invention. Setting and preferences that relate to the client device's operation.

0024Server-side operations: • Servers are responsible for establishing and maintaining connections between users. Multiple users may be connected to each other at any one time such that a single voice-message may be sent to multiple recipients. • A server may disconnect the client when necessary (for instance if the client has 'timed out') although this is normally the client's responsibility. • A server is responsible for maintaining user information including user profiles (settings and preferences), usage and account status and any other information that is relevant to the operation of the invention. • A server may allow other users to query the status of a user's connection in order to determine if a voice-chat or voice-conversation is possible. • A server may enable the long-term storage of voice messages for remote retrieval by the user • A server may facilitate communication between devices using different signal encodings, possibly including a bridge to the telephony network. • A server may be able to provide additional services to users other than the management of voice communications between users.

0025Within the client-server framework that has been defined a number of modes of voice communication are supported by the invention.

0026Store-and-forward Voice messages may be transmitted by users to the server for retrieval by the recipient(s) at a later date. Users connected to the server by internet (personal computer) or GPRS (mobile device) may be notified by the server when a new message is received and may download the message at that time. Store and forward mode of operation enables low bandwidth signal encoding techniques to be used as there is no requirement for real-time transmission. Users connecting to the server by conventional telephone may check for and receive messages by placing a call with the server.

0027Voice Chat Communications between users may be carried out in real-time using a voice chat facility. Users may record and transmit voice messages only to other users who are connected to the server. This obviates the need for the server to store messages. As clients can only listen to a single incoming message or record a single outgoing message at one time it will be necessary for the client device to store incoming messages as they are received and playback is initiated upon the user's request. This also provides users with the option of long term storage of voice-chat sessions. The single-duplex nature of voice-chat communication still allows for low-bandwidth transmission methods to be pursued with moderate signal delay.

0028Voice Conversation Users may 'call' other users who are connected to the server on a 'full-duplex' (simultaneous, two-way) channel. As all calls are routed through the server connections between more than two participants may be possible where each client only has a single outgoing and incoming voice channel and the server conducts the necessary mixing of the conversation participants. Voice conversations of this nature require low-signal delay to be of the utmost priority, although proprietaiy encoding techniques may still render some bandwidth savings in comparison to conventional techniques that are used by mobile telephony and VoIP service providers.

0029Brief Description of the Drawings

0030The description of the invention accompanied by the figures in this document which are described as follows:

0031Figure 1 is a diagram of the framework of the invention which incorporates a means for encoding and decoding voice/audio data, a means for transmitting that data and a client- server infrastructure that facilitates the communications between clients.

0032Figure 2 is a diagram of a data connection between a client's mobile communications device and a server.

0033Figure 3 is a diagram of an internet data connection between a client's computing device and a server.

0034Figure 4 is a diagram of a connection between a client's conventional telephony device and a server.

0035Figure 5 is a diagram of an example of client information/profile/preferences management system where client #1 has access to his/her profile and preference details stored on the server and local device, whereas client #2 may only access limited details pertaining to client # 1 's server stored data.

0036Figure 6 is a diagram demonstrating the management by a server of connections between a number of transmitting client devices and a single receiving device. This includes the conversion between different signal encodings and handling of connections between many (greater than two) participants. Each client device has a similar transmission and reception relationship with the other devices connected to the server. Figure 7 is a diagram of the store-and-forward mode of voice communication. In this diagram the transmitting client sends a store and forward encoded message to the server which then notifies the intended recipients that a message is waiting to be downloaded from the server. Each recipient client device individually notifies the server that they wish to download the message and the server follows this instruction. The recipient client device receives the encoded message and reconstructs this on the client device. When all recipient clients have received the message the message is expunged from the server.

0037Figure 8 is a diagram of the instant messaging mode of voice communication. Messages received from the server by a transmitting client device arc forwarded on immediately to all connected recipient client devices. Messages are stored on the recipients' devices for later review by the recipient.

0038Figure 9 is a diagram of the conversational mode of voice communication. The server receives encoded voice data from all conversation participant then performs the encoding conversions and signal mixing prior to forwarding the intended voice data to each recipient.

0039Figure 10 is a diagram showing ho additional voice services may be provided to the client via the client-server infrastructure. A client makes a request for a service provided by the server which is acknowledged by the server. The server then indicates that it is ready to process the client's data which once transmitted by the client is processed by the server and the result is sent back to the client. Detailed Description of Preferred Embodiments

0040The invention is described in further detail by way of example making reference to the accompanying diagrams. Each embodiment will also include references to the claim which it is exemplifying, although the claims are not limited to such embodiments.

0041Figure 1 shows a block diagram of a framework for the delivery of voice communications services between mobile devices and to/from mobile devices to other communications devices according to claims 1, 2 and 3. Connections with the server are established by client devices as shown in Figures 2, 3, and 4 and the server then routes communications between the client devices according to claim 4.

0042In order to connect with the server clients must do so using either the proper software installed on their device according to claim 5 or via a bridge with the conventional telephony network. Clients connecting via software may have immediate access to their own personal profile that is stored on the central server, while personal settings such as a 'phone book' may be stored locally on the client device or centrally on the server (or both). When connecting via a bridge with the telephony network the range of services available may be limited due to security issues.

0043Management of client profiles and preferences including but not limited to usage statistics, account information and a 'phone book' is carried out on the server and client devices according to claims 12 and 13. Clients may update the stored information (such as account balance) on the client or server devices using the installed software over a secure connection. Figure 5 illustrates the client pro file/ preferences management system.

0044In voice communications that are made via a centralised server the server is responsible for ensuring compatibility between different signal encodings (for instance a client using a VoIP connection wishes to talk with a client with a mobile device) according to claim 9. As there is only a single outgoing and incoming connection with the server from each client device the server is also responsible for the management of multiple simultaneous voice connections such that the incoming signal to a client device may be a composite of multiple incoming voice messages from different senders. This is described by claims 14 and 16 and is illustrated in Figure 6.

0045Users may carry out voice communications using a number of different modes of operation three of which are detailed as claims 6, 7 and 8. In claim 6 users may send voice messages using a store-and-forward system as illustrated in Figure 7, in claim 7 users may send instant voice messages to one another as illustrated in Figure 8 and in claim 8 normal telephone style conversation is supported as illustrated in Figure 9. The main differences between the different modes are highlighted in the accompanying figures. Other modalities of voice communication are also possible. Those which are simply an elementary modification or combination of the modes listed explicitly here are also intended to be covered by this document.

0046The installed software on the client device is responsible for encoding the captured voice/audio signal into the transmitted data format and for decoding and reconstructing this signal from the transmitted data format according to claims 10 and 11. The user is able to select desired signal quality/bandwidth of the encoded signal and the service provider may also limit the bandwidth/signal quality due to infrastructure limitations. This is described by claim 18. The coding scheme in claim 1 also may enable user customisation of the voice reconstruction properties such as but not limited to pitch, timbre and speed. The software for signal encoding and decoding is upgradeable to support improvements made to bandwidth and/or quality of the signal encoding method according to claim 17.

0047Voice communication in all three modalities supports the option for the long term storage of voice recordings either on the device or on the central server according to claim 15. Voice recordings may be re-encoded using a lower bandwidth scheme on the server or client device to enable the more efficient storage of the recording. For the voice store- and-forward messaging system messages can be stored by requesting messages be moved from short term to long term storage on the server. Similarly for the voice chat system, messages can be stored by requesting messages be moved from short term to long term storage on the client device. In the remaining cases for voice store-and-forward, voice- chat and voice-conversation the server or client device can be requested to store voice data relating to the client. This must be done prior to the client carrying out the voice communication otherwise the data is lost once it is processed by the client device. It is also possible to copy stored voice data to/from the server/client device.

0048Additional services may be provided by the server to connected clients according to claim 19 as illustrated in Figure 10. Such services may include (by way of example and not definitive) voice dictation services, recognition of captured audio with databases of such audio (for instance recognition music samples via the device).