INTRODUCTION

In 1992, Voxson Limited (then Voxson International PTY LTD) was applying for Australia’s Third Carrier Licence in partnership with Celcom Malaysia.  Voxson/Celcom and Vodafone were the competing bids in the last selection stage with Voxson eventually being outbid by Vodafone.

In order to provide differentiation from the then existing two Carriers (Telstra and Optus), a strong component of the Voxson/Celcom licence bid involved two components:  the integration of network-derived GPS data into the Cellular Network and an implementation of multi-channel broadcasting for broadband implementations such as video-on demand and video telephony.  These two technologies are now used in Assisted GPS and HSCSD/GPRS broadband respectively. 

Also in 1992, coincident with the preparation of the Third Carrier Licence Bid, Voxson applied for two patents based on these technologies, known as VOX-1 and VOX-2.  Both are essential technologies under the ETSI standards.  The ETSI standard relevant to VOX-1 is 3GPP TS 22.071 V7.4.0 (2005-12) [Sections 4.16 & 4.17].  The standards relevant to VOX-2 include, but are not limited to, HSCSD, GPRS, EDGE, W-CDMA (UMTS), IS-95, and CDMA2000.

VOX-1
INTEGRATION OF CELLULAR MOBILE COMMUNICATION NETWORKS AND GLOBAL NAVIGATION SATELLITE SYSTEMS

International Patent Document – PCT/AU93/00614   EP 0 681 704 B1 – VOX-1
ETSI Standards regarding VOX-1
Registered Countries for VOX-1
Documents and links which have relevance to the Voxson VOX-1 Patent
VOX-1 Patent Explanation

DOCUMENTS AND LINKS WHICH HAVE RELEVANCE TO THE VOXSON PATENTS.

VOX-1: Assisted GPS patent

Highlights from Links below

How it Works- http://www.positionmag.com.au/GU/content/1997/GU23/gu23_DGPS.html

Geolocation and Assisted-GPS – by Goran M. Djuknic and Robert E. Ricton. Bell Laboratories, Lucent Technologies

Introduction to GPS Data NMEA & RTCM – by Donald Choi, ALS/G2

DGPS Data Formats 2.0 – by Andreas Bagge

Vannucci; Giovanni – US Patent number 6,118,977 – An expansion on VOX-1 and post-dated to VOX-1

Sheynblat – US Patent 5,999,124 – Owned by Snaptrack a Qualcomm company - Similar to VOX-1 and post-dated to VOX-1

Motorola – US Patent 6,313,787 – Similar to VOX-1  and post-dated to VOX-1

VOX-2

Position on Infringement Vox-2 Snap Overview

Nokia – Patent WO 98/59441 – Similar to VOX-2 and post-dated to VOX-2

Siemens – US Patent 5,648,967 - Similar to VOX-2 and post-dated to VOX-2

Patent Explanations

 VOX-1:

The principle behind the first differentiation was to provide mobile users with information about the GPS signals they would be receiving by collecting and/or correcting similar signals from the same satellites at nearby cell sites.  These cell sites are intrinsically in close proximity (a few kilometres) to the mobiles which they are servicing and therefore the GPS signals received by the cell sites and the mobiles will share many similarities, such as ionospheric and tropospheric delays, Doppler shifts, satellites in view, time etc.  The elevated and known locations of receivers on the cell sites can provide very high quality GPS data, giving continuous tracking, low multipath effects, ephemerides (orbit information) and even carrier phase ambiguities etc.  This is in contrast to signals received in mobiles, which are subject to fading, satellite occlusion, poor signal level due to trees etc.  The data received or calculated at the cell sites can be broadcast to the mobiles to assist in correcting errors, providing warm-start information, providing satellite ephemerides, and providing information on the integrity of the system.  The system can be used either to aid in the calculation of a position and/or in the correction of that position by differential subtraction of errors measured at the cell site.

VOX-1 discloses a system of transmission of local GPS data, measured or calculated at the cell sites, to the mobiles.  The inventiveness of the patent is associated with the method of transmitting the information to the mobiles, a method which was not being used in conjunction with GPS by any other groups ‘skilled in the art’.  It is important to realise that the reason for this was that, in 1992, there was a class of people skilled in the art of GPS while there was a different class of people skilled in the art of cellular networks.  For the Third Carrier Bid, Voxson brought together experts in GPS and its own experts in cellular mobile technology.  VOX-1 is a patent which joins together, in an innovative way for that time, the solution of a number of GPS problems, by embedding GPS into the underlying structure of cellular (and related) systems.

It was proposed that the data be sent over a ‘special signaling layer’, a term intended to refer to the layer of network control and messaging which is used within the network to communicate information to the mobiles concerning the operation of the network, the connection of the mobiles, hand-over from one cell site to another and other messaging channels.  This ‘special signaling layer’ is capable of sending messages to individual or groups of mobiles as a broadcast and is transparent to the user, i.e. the user is unaware of the presence of these signals and is not charged for them.  The addition of two-way GPS data to the normal signaling. messages would not significantly reduce the capacity of the network.  The network operator would have total control of these signals and can choose to charge for the service when it is used if so desired.

SUBSEQUENT IMPLEMENTATIONS

It was not until 1997 that other companies worked towards the implementation of such a system.  Lucent and SnapTrack each submitted patents which build on the ideas in VOX-1.  The system is now known as A-GPS (Assisted GPS).  Shortly afterwards, Qualcom purchased SnapTrack and its patent portfolio and commenced work (in conjunction with GPS manufacturers) to implement the system.  This effort gained momentum when the United States introduced its so-called E911 legislation, which mandated the location of the majority of Emergency 911 calls from mobiles.  This was to mirror the capacity of the fixed-line systems to do so and also had some basis in National Security issues.  The systems are presently being introduced in a number of mobile phones and within a short time, the majority of mobile phones will be fitted with A-GPS solutions.  Other countries will follow the lead of the US in the legislation of E911.  However, the real impact of this technology will be realised through commercial uses of the system for security and vehicle and personal tracking.

MORE DETAILED DESCRIPTION

The basic system is shown below.

The GSM mobile cellular system includes an increasingly large number of cells with which the mobile stations communicate.  These cells are transmitting and receiving sites distributed in a network of locations separated typically by distances of between ten kilometres and some hundreds of metres, depending on the density of the expected data traffic.

The GNSS system (GPS at present and including the European Galileo system in the near future) is a satellite based network which provides information to a mobile receiver, which can be used to calculate its position in three dimensions anywhere on or above the Earth's surface.  The accuracy of such measurements is limited by natural disturbances such as reflections, noise, the Earth's irregular atmosphere and ionosphere and the speed of acquisition of the signals depends on the amount and accuracy of any a-priori data available.  Measurements of integrity depend on other networks which measure integrity data, such as a mobile network.  This network sends integrity data to the mobile stations.

Virtually all types of errors and other useful data can be measured at a surveyed site of accurately known position.  Any other receiver in the vicinity of this site will be receiving similar data, so such things as differential compensations can be applied if these errors can be made available to the mobile receiver.  This is referred to as Differential-GPS (D-GPS).  The normal error without compensation is of the order of up to 15 metres.  This can be reduced to about one metre for every one hundred kilometres between the user and the surveyed site.  For example, in the case of sites of ten kilometres separation, such as in the cellular network, the maximum position errors in a D-GPS system can be reduced to less than one metre, depending on the number of satellites mutually visible by the mobile user and the surveyed site.  The number of suitable applications is increased significantly by this enhanced accuracy.

In emergency situations, such as a car accident or during an emergency call, it may be necessary to obtain a position fix in very short time.  Assisted or Aided GPS (A-GPS) is initiated by a call for help or triggered by an emergency event by sending a message via GPRS to a service centre or network.  The network knows the approximate position of the mobile device from the position of the cell site connecting the call and can quickly determine the data required to enable the GPS receiver to lock on to the satellites immediately (satellites in view, pseudo-ranges, Doppler shift information, ephemeris etc).  Special GPS receivers can calculate the position from cold within one second of receiving this information.  A-GPS receivers can also receive much weaker signals since they don’t need first to decode certain information which is sent to them, often allowing location fixes to be made inside buildings and car parks.  These systems can then provide a fast position reporting service for vehicle dispatch subscribers who wish to access the position of their fleet or for security service providers who receive reports of lost vehicles or hazardous situations. 

The network derived data can also be included in mobile station information which is broadcast to all enabled mobiles at the same time and continuously if desired.  It is believed that the two-way flow of information (D/A-GPS data from cells to mobiles and position reporting from mobiles to cells) could be accommodated in the normal message service layers of the cellular mobile system at very low cost.

The large number of cell sites available in a mobile cellular network and their close separation provide an ideal infrastructure for a D/A-GPS network.  Most modern cellular base stations already contain a GPS receiver, providing accurate timing signals.  Each cell communicates regularly with all active mobile stations in its vicinity, sending and receiving identity and other system information.  The user is unaware of this information.  GPS data can be added to this information, automatically providing a continuous D/A-GPS facility to anyone using a GPS receiver for position determination.  The cost of implementing such a system is minimal, since cells and mobiles communicate regularly at little or no cost using these signaling. messages.  The cellular mobile provider is a key component of the system.  Provision of the data could be on the basis of an additional service paid for by those desiring it.

VOX-2:

In 1992, Voxson was considering the use of multiple mobile channels to enhance the available bandwidth required to implement a video-on-demand system which it was beginning to develop.  At that time, video phones and the like were limited to fixed wire systems and the idea of having a video phone using mobiles was not being contemplated within the standards being set for mobile systems.  It was not until 1997 that such standards were introduced within the HSCSD standard, which was subsequently expanded to GPRS, EDGE, W-CDMA (UMTS), IS-95, CDMA2000, etc.

At that time, mobile networks were focussed on voice data due to the low basic bandwidths which were available on each channel and it was not until the digital technology became reasonably mature in the mid 1990’s that digital data was actually implemented, paving the way for messaging, image transmission and ultimately the use of multiple channels to send information.  VOX-2 was well ahead of its time in proposing such a system.

Back in 1992, the implementation of these two systems in the Voxson/Celcom bid would have provided significant differentiation for the Voxson/Celcom network, had the bid been successful.