Patent Application
20060212179
The present invention relates to a stand-alone car receiver for a car entertainment or infotainment system.
Car entertainment and car infotainment systems are becoming more and more complex. Customers are interested in having increased functionality and connectivity in an integrated system. In order for these systems to become a commercial success, technical solutions enabling cost reduction for the use of these multimedia devices by the average user will be needed.
The software defined radio (SDR) concept is used to describe radios that provide software control of a variety of modulation techniques, wide-band or narrow-band operation and waveform requirements of current and evolving standards over a broad frequency range. It is applicable across a wide range of areas within the wireless industry. With SDR, one aims to implement a common hardware platform and accommodate various standards and technologies via software modules and firmware.
Multimedia systems are becoming more and more apparent in the automotive and mobile market. Currently, DAB, T-UMTS and DVB-T are formats capable of delivering multimedia information to car-mounted systems. Another technology that can serve this market is WiMAX IEEE802.16, and especially the Mobile WiMAX IEEE802.16e variant, which will provide internet access to mobile platforms using an extension of the WLAN technology. Similarly there is 802.MBWA (Mobile Broadband Wireless Access). Although not being a broadcast or multicast technology, WiMAX could develop quickly on a commercial basis and should therefore not be ignored for this type of car based services. The quantity of systems in the field is also increasing, and therefore extra broadcasting layers are proposed such as Multimedia Broadcast Multicast Service (MBMS). Car systems also need the reception of GPS or Galileo signals in order to allow location based services to become more effective in front of the growing user community.
The connectivity problem is mainly reflected in the cost of integrating multimedia systems in a car environment. Additional peripherals need to be installed such as an information bus, extra displays, . . . Today the average user is not able to spend a large amount in order to afford the system, making it suitable only for the high-end system niche.
The main disadvantages faced by the current users are the cost and the quantity of separate receiver modules needed to support the different formats. Special receivers need to be purchased in order to have the necessary functionalities requested by the end user. Current consumer products support FM and DAB reception. Except for high-end cars, GPS (or future Galileo) reception requires the user to purchase an additional receiver that is mounted in the car. The current technical solutions have already reached some inter-system interaction level such as GPS/RDS, but no solution has been found yet for future interaction between e.g. Satellite Digital Multimedia Broadcast (S-DMB) and Galileo. Most of the information received is currently audio and can be played through the car's audio system. Future systems will provide multimedia content (including images and video) and will need new user interfaces in the car, which can be expensive.
The S-DMB concept is a concept originating from the mobile market. Its purpose is to broadcast multimedia information towards mobile users on their 3G handhelds. The S-DMB concept is a satellite based overlay system of the 3G terrestrial networks. However, S-DMB suffers from a limited indoor penetration and a poor coverage in some environments (e.g. shadowing, large multipath profiles, . . . ). The S-DMB concept is currently not addressing the automotive entertainment industry. However, S-DMB service reception in the car is beneficial for the car passenger entertainment and ‘infotainment’ as push and store and streaming services are provided.
Patent document EP1152254 (also U.S. Pat. No. 6,351,236) relates to a mobile transceiver that combines GPS and CDMA. The receiver is equipped with both a CDMA Tx/Rx antenna and a GPS Rx antenna. Separate GPS and CDMA sections are used to process the respective signals. A select path selector is foreseen to select the appropriate section.
WO97/14056 discloses a combined GPS positioning system and communications system utilising shared circuitry. It also requires a GPS antenna and a communication antenna. The integrated communication receiver may include a component, which is shared with the GPS system. It mentions a processor that is supposed to perform the demodulation and the processing of GPS signals and communication signals. The GPS operation and the communications reception/transmission operation are typically performed at different time instants, which facilitates the use of common shared circuitry. In addition, the signal processing operations for the GPS signals is performed typically in a programmable DSP. No receiver architecture is disclosed.
In patent application EP1054265 an apparatus is disclosed for performing spread spectrum-based communication and navigation on a single device. The apparatus is provided with a receiver suitable for receiving spread spectrum-based signals as well as satellite navigation signals. The apparatus further comprises a number of tracking units that are programmable in either a navigation mode or in a communication mode and a processor.
Patent application EP 1349289 is related to a terrestrial UMTS or equivalent terminal for the reception of broadcast and/or multicast information. The terminal comprises a baseband processor that is reconfigurable for terrestrial and satellite UMTS or equivalent reception. It further comprises an internal RF front-end for terrestrial reception and a connector at intermediate frequency arranged to connect an external RF front-end for satellite UMTS reception.
The present invention aims to provide a cost-effective car receiver with a low power budget that can be used in combination with a variety of broadcast and navigation signals.
The present invention relates to a receiver system comprising a receiver module, a server subsystem to handle received data, a local storage device to retain said received data and a connectivity box for connecting external communication links.
In a preferred embodiment the local storage device is a hard disk or a DRAM memory device or a non-volatile memory device.
The connectivity box advantageously is arranged for providing a wireless link to connect a user terminal. The wireless link preferably is a WLAN or a Bluetooth interface link. In a preferred embodiment the user terminal is a mobile phone. Said mobile phone may be used as a Graphical User Interface for the applications running on the server subsystem. Alternatively the mobile phone is used to get access to missed packets via the terrestrial (cellular) network, and in this way to synchronise the data in the local storage of the car receiver with the data at the source side, i.e. at the remote server. The connectivity box may further provide a connection to a vehicle network, e.g. a MOST (Media Oriented Systems Transport) network.
Preferably the receiver module in the receiver system is a reconfigurable digital receiver module comprising
Advantageously the sampling means receive the received waveform via a RF circuit. The functions specific for the waveform are preferably parameterisable.
In a further embodiment the reconfigurable digital receiver module further comprises an embedded processor subsystem arranged for performing at least one function from the group of functions comprising {initial digital receiver configuration, runtime digital receiver control, protocol stack execution}.
In a specific embodiment a programmable logic area is integrated in the parameterisable integrated circuit. Advantageously the programmable logic area further comprises the inner modem and/or outer modem hardware functionality.
The reconfigurable digital receiver module is configured for receiving signals according to an air interface standard of the group of standards {S-DMB, DVB-S, DVB-H, DVB-H+, DVB-T, GPS, Galileo, WiMAX IEEE802.16e, IEEE802.20 MBWA).
The present invention also relates to a wireless portable device comprising a receiver system as described above.
In a further aspect the invention discloses a car comprising a receiver system as described. Preferably the receiver system is then connected to the car power supply and/or to the car's vehicle network.
In another aspect the invention relates to a method to access a service available in a receiver system as previously described through a user terminal, comprising the steps of
In a further aspect the invention relates to a method to retrieve missing packets related to a service available in a receiver system as described, comprising the steps of
The method to retrieve missing packets related to a service available in a receiver system can be used in a similar way when an external access point is present. The method then comprises the steps of
The car receiver as disclosed in this invention is a stand-alone receiver for a variety of broadcast schemes and navigation signals. It has a considerable local storage capability and is e.g. to be installed in the car booth or as part of the board telematics compartment. It is a small box including an antenna to be mounted on the roof of the car. This antenna can e.g. be a patch antenna providing additional gain (as compared to e.g. the antenna of a handheld wireless device), in order to boost the quality of the reception. The box is connected to the car power supply and the car multimedia bus (e.g. MOST) if present.
The receiver system can operate as an integrated system in a car multimedia environment (if existing) or independently from the car's telematics system by using the mobile phone as multimedia user interface. The connection to the mobile phone is performed through a wireless interface (such as Bluetooth or WLAN).
The strength of a receive-only system for reception of broadcast and navigation information is in its relative simplicity: it can be realised cost effectively and with a low power budget. No transmit section is included, which allows for a much simpler RF front-end, and the transmit power, which is the bulk of the power budget in a bidirectional communications terminal, is obviously not present. There is also an important simplification in the development cycle, as the regulatory aspects do not include the requirements related to transmission (except for the usual EM compliance).
In many cases, return channels can be realised also by combining the above communication standards with terrestrial systems, such as the already existing GSM/GPRS/UMTS, WLAN IEEE802.11a/b/g/ or Mobile WiMax IEEE802.16e, which is under development.
Server processor (12) handles the control of the receiver module (11) as it receives new service data. The server also controls the streaming of received data to store locally on memory (13). It further takes care of the data interfacing with the MOST bus and the short-range link. On demand, the server sends the requested information stored on the local storage medium to the user. In case of a S-DMB receiver scheme, the server is also arranged to reconstruct missing data using the S-DMB carousel retransmit scheme. The server further also performs control and monitoring tasks and boots the receiver (11) at start-up. Using LAN (Local Area Network) and PAN (Personal Area Network) network interfaces, the server is able to connect to neighbouring mobile devices. With this local connectivity (e.g. WLAN or Bluetooth), the car receiver can connect to a mobile phone (that is equipped with a WLAN and/or a Bluetooth interface) for the following purposes:
The buffer memory (13) is a high-capacity storage device like a large compact flash or hard disk. Preferably there is at least 4 GByte of storage available, which is technically well feasible. Taking into account a user data rate of 384 kbits/s as is the case in one of the S-DMB modes, this allows for a continuous download duration of 23 hours. Note that e.g. in a standard S-DMB mobile handset terminal no such storage capacity is provided.
The connectivity box (14) links the receiver device (11) and its data to short-range wireless connectivity. Via a wireless link such as Bluetooth or WLAN a user terminal can be connected to the car receiver. The connectivity box (14) also provides a link to the car network. This is e.g. a MOST data bus interface, as it has good capabilities for multimedia transport in the automotive environment. The user can interact with the multimedia car environment and retrieves the data via the multimedia data bus of the car. Up to 50 Mbaud is supported, which is far more than the needs of the maximum user data rate and additional signalling that need to be handled. Data communication is taking place over an optical fibre network, requiring transducers between the electric and the optical domain.
A traditional state-of-the-art receiver typically comprises an RF front-end that downconverts, amplifies and filters the antenna signal, an A/D converter that digitises the analogue signal, and a digital demodulator which performs the specific demodulation of the waveform specified in the air interface for which the receiver is intended. Protocol handling is typically done in an (embedded) processor subsystem. In high-volume applications, such a traditional receiver might be implemented as an ASIC. A full implementation of the digital part in an FPGA (Field Programmable Gate Array) is typically only done for those applications where cost and/or power consumption are less critical. The FPGA principle is based on the ability that logic functions, interconnections and memory can be configured on largely programmable modules. The versatility comes at the price of higher power consumption and higher cost, especially for complex mobile systems.
Software Defined Radio (SDR) sometimes is interpreted as a pure software implementation on an architecture based on general purpose processors or DSP processors. While this might be a power-efficient solution in a distant future, it is not a feasible option for many years, if low power consumption is a design criterion. For at least another decade a combination of hardware (logic, fixed and/or programmable) and software is required, for cost and power reasons. The present invention describes a novel approach in which a high degree of flexibility, low power consumption and low cost of implementation are reached for a broad class of emerging communication schemes. In particular, the issue of combining broadcast reception and navigation is addressed (cfr. infra).
An important aspect of the architecture is that parallelism must be achieved, certainly at the highest level of the architecture, in order to optimise (i.e. reduce) power consumption. This means that the typical approach of using hardware accelerator processors, on a common bus of another (software) processor, is avoided, because this creates a high-speed bottleneck on the bus, resulting in high clock speeds and hence high power consumption. Instead, the architecture blocks must be as much as possible organised as a concatenation of modules, i.e. with dedicated buses in between, clocked at a speed, which is a small multiple of the sampling speed, or lower.
Both
The parameterisable ASIC (111) part can possibly be reconfigured through boot time or runtime parameter setting or updating. Parameter passing and control is executed by the processor subsystem. The ASIC contains flexible hi-speed hardware blocks, allowing the implementation of various receiver schemes on the car receiver SDR infrastructure, such as S-DMB, DVB-S or its derivatives, GPS, Galileo, etc. This includes blocks such as:
Programmable logic area (FPGA) (112) contains hardware blocks, which must be fully reconfigurable, such as W-CDMA specific functionality (Rake), DVB-specific functionality (high-speed error decoding), . . . Some hardware blocks are parameterisable as well, e.g. to switch between S-DMB speed modes, or to switch between communication reception (e.g. S-DMB) and navigation reception (e.g. Galileo). The trade-off to be made here is the choice between runtime reconfigurability and runtime parameter updating. As the high-speed, complex functions already are mapped onto the ASIC, the Field Programmable Gate Array (FPGA) can be kept relatively small and cheap. Moreover, it can be clocked at relatively low speeds, which is important for the power consumption. In this way, the disadvantages of the use of large FPGAs are avoided while the advantage of full reconfigurability of a smaller FPGA is maintained.
Processor subsystem (113) performs configuration control, executes protocol software, and lower-speed demodulation/decoding functions. Patent applications WO00/69086, US2002/0196754 and EP0767544 are hereby incorporated by reference.
It is also possible to simplify the required RF circuitry by moving the lowest IF into the digital domain. This reduces the component count or BOM (Build of Materials) and hence the cost. Sampling will then be at a higher frequency than in the case of the commonly used zero IF. This might be affordable given the fact that higher speed digital part is in ASIC (where the power penalty for higher clock speeds is not that high), not in FPGA or software.
Several examples of the mapping of receiver schemes on a SDR receiver module according to the invention are now presented.
A first instance relates to an S-DMB receiver. The carrier frequency is typically in the S-band (around 2 GHz). The bandwidth and maximal data rate are 5 MHz and 384 kbits/s, respectively. In order to meet the filtering requirements a bandwidth of 5 MHz is provided. No return link capability is required for the protocol. The receiver is built around a W-CDMA like demodulator. Digital downconversion, Root Raised Cosine filtering and sample rate adaptation (if needed) are functions handled by the reconfigurable ASIC.
The FPGA comprises part of the Inner Modem (IM) and most of the Outer Modem (OM) hardware blocks and an embedded microcontroller subsystem. The microcontroller runs RT (real time) software in support of the IM and OM hardware blocks. In the IM the following hardware blocks are provided:
An alternative receiver scheme could be a DVB-S derivative, with the following features:
A further possible receiver scheme is a scheme according to the DVB-T and DVB-H standard, with the following features:
An important case is that of GPS.
A further example relates to a device arranged for receiving Galileo navigation signals.
Wimax IEEE802.16e (and also IEEE802.MBWA that is related) are bidirectional WiFi-type of systems. They could possibly be mapped on the architecture if a return channel capability is also added to the architecture. Technically the SDR architecture presented can be extended in a straightforward way to address the transmit capabilities needed in the digital subsystem. The Wimax system has the following features:
The most important features of the various receiver schemes are summarised in Table 1, which lists the main implementation parameters for the S-DMB, Ku-Mobile (an S-DVB derivative), DVB-H, DVB-H+, DVB-T, WiMAX, GPS and Galileo use cases.
The RF frequency mentions the band, which has to be received by the external antenna and processed by the RF front-end. The A/D sampling requirements are set by the most demanding of the schemes we want to map on the SDR architecture. The maximum user data rate is listed. Some settings of the digital front-end ASIC are given, like filter bandwidth, resampling needs, use of the FFT-operation for OFDM demodulation, . . . The main specific demodulation and channel decoding functions for the FPGA target are given as well. The main software processing functions for the embedded processor are given.
In the paragraphs below, an example of a possible implementation of the car receiver is given.
A hardware case is designed in order to provide housing for the hardware components, mounting means for the car receiver and access to the I/O and power supply connectors. The hardware box will carry the following elements:
Advantages of the invention are manifold. It offers a solution for the architecture of a device for addressing multiple broadcast formats in an efficient way. More in particular, it contains
The embedded processor handles the received data, interfaces with the wireless connectivity provisions and with the car's multimedia bus, and supports the application processing. The wireless connectivity can be used to link the car receiver with an external mobile phone. This allows to use that external handset to act as a GUI for the applications running on the server subsystem, or to retrieve missing packets, through the cellular link that can be set up via the handset.
There are multiple advantages
Also for the end user the solution according to the invention offers many advantages:
Applications of a miniaturised broadcast receiver are manifold and include:
| Number | Date | Country | Kind |
|---|---|---|---|
| 0504824.4 | Mar 2005 | GB | national |
