WO2003072398A1 - Optical networks and methods for use in automobiles and other mobile vehicles - Google Patents

Abstract

A vehicle is equipped with a network that permits multiple units to communicate with each other over a common optical bus. The optical bus is bi-directional and couplers direct optical signals that travel in both directions along the bus toward the various units connected to the bus. These couplers also direct optical signals from each unit onto the bus in both directions. The units may form part of one or more systems, such as an entertainment system, engine system, or data and communication system. The optical networks are immune to electromagnetic noise that may be generated within the vehicle and significantly reduce the amount of cabling compared to conventional electrical networks. The optical network can accommodate large numbers of units and systems by employing amplifiers dispersed throughout the network. The amplifiers compensate for splitting losses associated with the couplers and may be located along the bus or within the couplers.

Description

OPTICAL NETWORKS AND METHODS FOR USE IN AUTOMOBILES AND OTHER MOBILE VEHICLES

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to U.S. Serial No. 10/078,962 filed on February 20, 2002 entitled "Optical Networks and Methods for Use I n Automobiles and Other Mobile Vehicles," now pending.

FIELD OF THE INVENTION The invention relates to optical networks and methods for use in mobile vehicles and, more particularly, to systems and methods for permitting communication between units within the vehicles over a bi-directional optical bus.

BACKGROUND

Vehicles, and in particular automobiles, are being equipped with increasingly more advanced electronics. Originally, the electronics within an automobile were almost exclusively dedicated toward operation of the engine and other standard components of the vehicle, such as headlights, wipers, alternators, and blinkers. The electronic controls on many modern vehicles include firing control for multi-valve engines, cruise control, electronic locks, air bag controls, ambient air controls, temperature sensors and gauges, and other sophisticated electronics.

In addition to electronics dedicated to operation of the vehicle, automobiles are increasingly being equipped with additional types of electronics. For example, vehicles commonly have some type of an audio entertainment system, such as a receiver, CD or tape player, equalizer, and speakers. Many vehicles are also being equipped with security systems with the associated alarms, locks, keypads, remote controller, and siren. More recently, vehicles are equipped with navigation systems, such as Global Positioning Systems (GPS), and video entertainment systems, which may include displays, speakers, and DVD players. Vehicles are also being equipped with mobile communication systems, such as mobile radiotelephones, and soon will be equipped with some form of Internet access. This trend toward increased complexity and enhanced functionality provided within vehicles will likely continue in the years to come. For example, development work is already underway on adding intelligence to the vehicle to allow the vehicle to automatically drive within a lane at controlled distances to other vehicles.

These systems that are being added to vehicles add a considerable expense to the overall cost of the vehicle. In addition to the components themselves, the addition of these systems to the vehicle is not easily performed. For instance, each of these systems has its own power requirements with each system draining power from the battery and/or alternator within the vehicle. The limited amount of power generated by the alternator may be insufficient to meet the power requirements of all of these systems, thereby placing a drain on the battery.

Furthermore, manufacturers of the vehicles or installers of these systems must contend with placing cable throughout the vehicle for the various sensors, speakers, processors, and other components within the systems. This cabling is not only difficult to install within the small space of a vehicle, but renders it extremely difficult when a fault occurs and efforts are made to fix it. It may be difficult to differentiate between the wires associated with one system from those in another and furthermore may be difficult to trace connections between the various components within a system. The cabling can therefore present substantial challenges in installation and repair.

These various systems that may be placed within a vehicle are subject to other challenges. For example, the engine compartment of a vehicle contains a high degree of electromagnetic noise from the alternator, regulator, distributor, and other electrical components within the vehicle. This noise can be picked up by any of these systems and the wiring connected to these systems and interfere with normal operation of the systems. To suppress this electromagnetic noise, the systems need to incorporate filters, signal processing, and electromagnetic shielding, which further increases the costs of these systems and thus of the vehicle.

To address the electromagnetic noise problem, optical networks have been proposed for use within a vehicle. For example, U.S. Patent No. 4,948,218 to Kobayashi et al. describes the use of optoelectronic devices at various units within a vehicle, such as at an engine revolution indicator, distributor, controllers for headlights, and controllers for blinkers. These optoelectronic devices are coupled to each other via an optical fiber to permit a serial multiple bus type communication of data and control signals between the units. This system is described as reducing the multitude of electrical wiring which was necessary in conventional systems and has the benefit of being immune to electromagnetic noises generated near the engine. The system is also described as being able to be implemented in a small space and at a low cost.

One drawback to such optical networks within vehicles is that they are limited in the number of units that can be connected to the optical fiber. A fraction of the optical signals traveling along the fiber is diverted to each unit. Consequently, after a certain number of units have received their share of the optical signals, the remaining signals on the fiber are at such a low level that they cannot be detected by downstream units. For example, such an optical network may only be able to accommodate a maximum of eight to ten units. As should be apparent from the description above, many of the systems may require a greater number of units coupled to the optical fiber.

One way to increase the capacity of an optical network is to perform wavelength division multiplexing ("WDM") of the signals. With WDM, one group of units can communicate with each other at one wavelength while a second group of units can communicate over another wavelength. WDM offers the ability to introduce a large number of wavelengths onto a single fiber, thereby increasing the number of groups. While WDM does offer the ability to have more components connected to an optical fiber, WDM increases the cost and complexity of an optical network since the units need to transmit and receive at different wavelengths of light. Furthermore, even though WDM allows more components to be connected to the optical fiber, for each wavelength of light, the number of units that can communicate at that given wavelength is still limited to a relatively small number, such as eight to ten.

Another approach to increasing the capacity is to add separate fibers, such as one fiber for a security system and another fiber for the entertainment system, histead of assigning fibers to a system, fibers can additionally, or alternatively, be added so that one fiber is for communication in a downstream direction and a second fiber for communication in an upstream direction. These extra fibers, however, also increase the cost and complexity of the network.

A need therefore exists for optical networks for use in vehicles that are not susceptible to electromagnetic radiation and can accommodate a large number of units.

SUMMARY The invention addresses the problems above by providing vehicles having networks for optical communication. Networks according to the invention comprise a bi-directional optical bus for carrying optical signals between a plurality of units. Each unit is coupled to the optical bus through a passive optical coupler which directs optical signals traveling in either direction along the bus toward the unit and which impresses optical signals from the unit onto the optical bus in both directions simultaneously. The networks also include amplifiers that perform bidirectional amplification of the optical signals.

Networks according to the invention are suitable for use in automobiles as well as in other types of vehicles. The networks are immune to electromagnetic radiation since the units transmit and receive optical signals. The networks also present a low weight and lower complexity due to the use of a single bi-directional optical bus. Furthermore, unlike some conventional optical networks, the networks according to the invention can accommodate large numbers of units and thus can be expanded well beyond 8 to 10 units, such as to 256 or more units.

The units connected to the optical bus are part of one or more systems associated with the vehicle. One of these systems can be a engine system which monitors and possibly even controls aspects of the vehicle's operation. Other systems include, but are not limited to, an entertainment system for providing audio and/or video, security system, data system, and communication system. In conventional vehicles, these types of systems are typically entirely separate from each other, each system having its own wiring. With a network according to the invention, the systems share a common optical bus, thereby greatly simplifying the cabling, testing, and maintenance. The networks according to the invention also enable integration of the disparate systems whereby a common processor can be used for functions normally associated with different systems, such as one processor for the communication, engine, security, and entertainment systems.

Other advantages and features of the invention will be apparent from the description below, and from the accompanying papers forming this application.

BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention and, together with the description, disclose the principles of the invention, hi the drawings:

Figure 1 is a diagram of a vehicle equipped with a network according to a preferred embodiment of the invention;

Figure 2(A) is a schematic diagram of an engine system forming part of the network of Figure 1;

Figure 2(B) is a schematic diagram of an entertainment system forming part of the network of Figure 1; and

Figure 2(C) is a schematic diagram of another system forming part of the network of Figure 1.

DETAILED DESCRIPTION Reference will now be made in detail to preferred embodiments of the invention, non- limiting examples of which are illustrated in the accompanying drawings.

I. Overview

An example of a vehicle 20 equipped with a network 10 according to a preferred embodiment of the invention is shown in Figure 1. The vehicle 20 in this example is a passenger automobile but can be comprised of other types of vehicles, including but not limited to vans, trucks, busses, motorcycles, tractors, and heavy machinery. The vehicles 20 are not limited to land or underground vehicles but also encompass boats, submersible vehicles, airplanes, spacecraft, and balloons.

The networks 10 include a number of units 12 which are joined to a bi-directional optical bus 14 through Optical Interface Devices (OIDs) 16. h order to minimize the number of wavelengths used on the bus 14, the networks 10 preferably employ only one wavelength, although the networks 10 may operate at more than one wavelength. The networks 10 may alternatively, or additionally, provide time divisional multiplexing access, such as described in co-pending U.S. patent application Serial No. 09/924,651, filed August 8, 2001, which is incorporated herein by reference. The OIDs 16 may comprise any suitable structure for directing optical signals from each unit 12 onto the optical bus 14 in both directions and for directing optical signals traveling along the optical bus 14 in both directions toward each unit 12. Some examples of such OIDs 16 include simple add-drop couplers, tunable filters, taps, circulators, wavelength division multiplexers, or couplers described in U.S. Patent Nos. 5,898,801 and 5,901,260, which are incorporated herein by reference. The networks 10 according to the invention can carry any type of data, such as analog, digitized analog, digital, discrete, radio frequency, video, and audio signals. The units 12 can also operate under any media access, network, transport, session, presentation, or application protocol. These protocols include, but are not limited to, the Ethernet standard, as specified by International Standards Organization (ISO) 802.3, Mil-Std 1553, ARINC-429, RS-232, NTSC, PAL, RS-170, PAL, RS-422, NTSC, PAL, SECAM, AMPS, PCS, TCP/IP, frame relay, ATM, fiber channel, SONET, WAP, and InfiniBand. The units 12 may operate in accordance an encapsulation method described in co-pending U.S. patent application Serial No. 09/924,037 filed August 7, 2001, which is incorporated herein by reference.

Each unit 12 comprises an optical-to-electrical converter and may also include an electrical-to-optical converter. The electrical-to-optical and optical-to-electrical converters may be provided as part of an electro-optical interface circuit (EOIC) as described in U.S. Patent Nos. 5,898,801 and 5,901,260. The invention is not limited to the type of optical transmitter but includes LEDs and lasers, both externally and directly modulated. As will be appreciated by those skilled in the art, each unit 12 may also include translation logic devices and other devices used in the processing or routing of the signals. A preferred network is described in U.S. Patent No. 5,898,801 entitled "Optical Transport System," which is incorporated herein by reference.

The optical bus 14 is preferably a single-mode fiber that carries optical signals in both directions simultaneously to all units 12 connected to the bus 14. The optical bus 14 also preferably provides bi-directional optical amplification of the signals traveling along the bus, such as described in U.S. Patent Nos. 5,898,801 and 5,901,260. Thus, the amplification of the optical signals may occur along a section 14a of the bus 14 with section 14a forming at least part of the interconnection between two of the units 12. The optical amplification need not occur along the interconnection sections 14a but alternatively may be provided along paths 18 which interconnect the units 12 to OIDs 16. Furthermore, the optical amplification may occur within the units 12 or within the OIDs 16. The optical amplification may be performed through fiber amplifiers, such as erbium-doped fibers or other rare-earth doped fibers, as described in U.S. Patent Nos. 5,898,801 and 5,901,260. The amplification may also be performed by devices separate from the fiber, such as any of the various discrete laser amplifiers or solid state amplifiers.

Significantly, the amplification that occurs within the network 10 associated with each unit 12 compensates for splitting losses to and from that unit 12. In other words as optical signals travel down the bi-directional optical bus 14 and encounter an ODD 16, a fraction of the optical signals is diverted to the unit 12. To compensate for this loss in signal strength, the optical signals are amplified, such as up to their original level, to maintain signal quality and strength. Thus, when the signals arrive at the next downstream unit 12, the optical signals are at a level which can be received and processed by the unit 12. This process of diverting signals to each unit 12 and amplifying the signals continues at each unit 12. While each unit 12 preferably has an associated amplifier, it should be understood that the amplifiers may not be associated with every unit 12 but should be dispersed throughout the network so as to ensure sufficient signal strength for each unit 12.

The units 12 can provide varying levels of communication functionality. The units 12 may include only a receiver for detecting communications from the other units 12 and may have a transmitter for sending communications to the other units 12. The units 12 may also include additional functionality, such as a display interface. Networks 10 according to the invention may include other numbers of units, may include additional or fewer types of units, and may include only one type of unit. Additional details of the units 12 will become apparent from the description below.

The optical network 10 provides a number of advantages over existing systems that are installed in vehicles. For one, the units 12 communicate with each other through optical signals. Consequently, the network 10 enjoys immunity from electromagnetic noise whereby the alternator, regulator, distributor, and other electrical systems within the vehicle 20 do not cause interference with normal operation of any one of the units 12. Furthermore, the optical network 10 includes a single bi-directional bus 14 which can be used to interconnect a large number of units 12 that form part of one or more systems installed within the vehicle 20. For example, the network 10 can accommodate in the range of 256 to 2,200 units 12 on the single fiber 14. The network 10 therefore presents a viable solution for systems having more than eight to 10 components and, moreover, presents a single solution that can integrate multiple systems. Another advantage of the network 10 is that it greatly simplifies the amount of cabling that needs to be installed within the vehicle 20. As mentioned above, the network 10 employs a single bidirectional bus 14 with every unit 12 being connected to this one bus 14. This single bidirectional bus 14 greatly simplifies not only the installation of the network 10 into the vehicle 20 but also the maintenance and repair of the network 10.

II. Engine System

An example of a first system 30 that may form part of the network 10 will now be described with reference to Figure 2A. The system 30 in this example is an engine system for use in monitoring or controlling operation of the vehicle 20. The engine system 30 includes a number of sensors 32 for detecting various parameters of operation of the vehicle 20. The sensors 32 may be for an engine revolution sensor, temperature sensor, fuel level sensor, as well as other sensors or detectors that exist now or are later developed. The engine system 30 may also include displays for the driver, such as gauges 34 and displays 35. The engine system 30 may also include audible indicators as represented by the speaker 36. The engine system may include a number of control systems, such as but not limited to, an engine control unit 38 for controlling such things as firing of spark plugs and control of valves, a locks/lights unit 40 for controlling the door locks and the internal and external lights of the vehicle, an anti-lock braking system unit 41 for control of brakes in the vehicle 20, a cruise control unit 43, a heating, ventilating, and air conditioning unit 44 for controlling the air and temperature within the vehicle 20, an auto pilot unit 45 for controlling the speed and direction of a vehicle 20, and an engine diagnostic unit 47 for monitoring the overall health of the vehicle 20. It should be understood that these units within the engine system 30 are just exemplary and that engine systems may include additional or fewer units.

The engine system can be used with any type of engine in a vehicle. For the purposes of this description, an engine is any system, device or assembly that produces a force that is involved in imparting a motion to the vehicle. These engines include combustion engines commonly found in most automobile and trucks but also include, but are not limited to, alternative fuel vehicles, electric vehicles, and hybrid vehicles.

As should be apparent from Figure 2(A), the network 10 can accommodate a system, namely system 30, which has more than eight to ten units 12. The engine system 30 includes units, such as sensors 32, that detect and transmit data onto the bi-directional bus 14, units such as gauges 34, displays 35, and indicators 36 which provide output to occupants of the vehicle, and units such as units 38, 40, 41, 43, 44, 45, and 47 that not only receive information from other units over the bi-directional bus but also transmit control signals and other commands onto the bi-directional bus 14.

III. Entertainment System

As mentioned above, the network 10 within the vehicle 20 may include an engine system 30 with a number of units 12 connected to the bi-directional bus 14. The network 10 is not limited to just one system but, as will be described in more detail with reference to Figures 2(B) and 2(C), may include multiple systems sharing a single bi-directional bus 14.

An entertainment system 50 connected to the bi-directional bus 14 will now be described with reference to Figure 2(B). The entertainment system 50 includes an antenna 52 and receiver 53 connected to the bus 14 through a coupler 16. The entertainment system 50 may also include an equalizer 54, front speakers 55, rear speakers 64, and a sub-woofer 65. The entertainment system may also include a display 58, and one or more drives, such as a cassette player 60, CD player 61, and DVD player 63. The receiver 53 can receive signals and place it on to the bus 14 with the equalizer 54 processing those signals and placing the processed signals onto the bus 14 for receipt by the various speakers 55, 64, and 65. In a similar manner, the signals from the players 60, 61, and 63 are provided onto the bus 14 and can either be picked up directly by the speakers 55, 64, and 65 or sent to the receiver 53 for amplification and then delivery to the speakers 55, 64, and 65. Other advanced functionality can also be provided by the entertainment system 50. For example, the entertainment system 50 may include microphones located throughout the vehicle 20 for providing feedback signals over the bus 14 to the receiver 53, such as for system optimization. The optimization provided by the receiver 53 includes, but is not limited to, optimizing acoustics, providing surround sound effects, and adjusting sound levels based on ambient noise.

As with the engine system 30, the entertainment system 50 may include more than eight to ten units 12 connected to the bus 14. The optical network 10 is therefore not limited to a small number of units as with conventional optical networks. Furthermore, the entertainment system 50 can be provided along with the engine system 30, thereby greatly increasing the number of units 12 communicating over the single bi-directional bus and making the information available for diagnostic testing and the systems connected easily accessible for software upgrades. IV. Communication and Data System

As demonstrated above, the network 10 may include multiple systems, such as the engine system 30 and the entertainment system 50. The invention is not limited to these systems but may have alternative or additional systems. As an example, the network 10 may include a data and communication system 70, such as the one shown in Figure 2(C). The data and communication system 70 may include a mobile voice communication unit 72, such as a mobile radiotelephone, satellite telephone, or radio. The data and communication system 70 may also include a mobile data communication unit 75, such as one providing internet access or access to other data networks. The data and communication system 70 can enable wireless communications over any number of frequency bands, such as but not limited to AM, FM, Weather, and cellular phone bands.

Some non-limiting examples of the mobile radiotelephone system include TDMA, CDMA, WAP, AMPS, PCS, GSM, NAMPS, USDC, CDPD, IS-95, GSC, Pocsag, FLEX, DCS- 1900, PACS, MIRS, e-TACS, NMT, C-450, ERMES, CD2, DECT, DCS- 1800, JTACS, PDC, NTT, NTACS, NEC, PHS, and satellite systems. Some non-limiting examples of wireless data networks include Cellular Digital Packet Data (CDPD), any other packet digital or analog networks, circuit-switched digital or analog data networks, wireless ATM or frame relay networks, EDGE, CDMA1, and Generalized Packet Radio Service (GPRS).

The system 70 may include other types of units, such as a GPS unit 73, and a voice recognition unit 78. The GPS unit 73 and the voice recognition unit 78 may communicate and coordinate with units in other systems, such as the entertainment system 50 or the engine system 30. The communication and data system 70 may also include input and output devices, such as a keyboard or keypad 79 and a display 76.

Each of the systems 30, 50, and 70 have been primarily described as being separate from each other in their operation but all connected to the common optical bus 14. The separation of the various units in these systems has been mainly for description purposes and it should be understood that the units within any of the systems 30, 50, and 70 may interface, supplement, and communicate with units in other systems.

Networks according to the invention provide a number of advantages over existing networks. For example, the interconnection of units to the networks is greatly simplified. Whereas before units were typically hard wired to a bus or to specific hardware interfaces, units can be added to the networks according to the invention at virtually any location along the bus. The units need not be located in close proximity to other units forming a system and also need not be wired to any dedicated interface. Instead, the units can be coupled to the bus through OIDs at a location determined to be most convenient.

The units can also be formed to have common components. Reference is made to co- pending U.S. patent application Serial No. 09/924,651 filed August 8, 2001, entitled "Fiber Optic Communication and Utility Systems and Methods" for additional details on the units. This commonality between units not only reduces manufacturing costs, but also greatly reduces logistics and support costs.

As another example, the networks according to the invention enables diagnostic of the systems and networks during operation. Some conventional networks require that the network be shut down to monitor operations and to perform maintenance or repairs. The networks allow for the monitoring of all communications being carried by the bus at any time and at any point along the bus. The networks according to the invention therefore enable non-invasive monitoring, maintenance, and repair.

The networks according to the invention also facilitates integration and cooperation among units and systems. Thus, each unit and each system can supplement and support other units or systems. The networks allow additional functionality to be provided in one system or in one unit at any time and to allow other units and systems to access the new functionality. In addition to relying on functionality provided in other units or systems, the units or systems can serve as a back-up or as additional capacity to the other units and systems. Thus, in the event of a failure or over-load situation, the units and systems can turn to the other units or systems on the bus for support. The flexibility of the bus also enables the networks to dynamically reconfigure themselves to optimize performance, such as based on the occupants of the vehicle.

The networks are easily upgradable. Rather than rewiring the network to include an additional element, a new unit can be added to the bus, again at any location along the bus. This type of upgrade is easy in the sense that there is no need to wire to other systems; instead the networks have an easily extendible bus. hi addition to hardware upgrades, units can also be upgraded through software. With both hardware and software upgrades, the units can be upgraded to have improved or new functionality.

The foregoing description of the preferred embodiments of the invention has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching.

Although many of the units described for use with the bus are internal to the vehicle, the invention can also communicate and interface with external units. For example, when a vehicle is parked, the vehicle may be physically coupled to another network, such as to replenish power supplies or to communicate with the vehicle. The vehicle may also be coupled to external units through a wireless interface. Thus, one of the OIDs may provide such an interface to external units, either by coupling to another bus or by providing a wireless interface.

The embodiments were chosen and described in order to explain the principles of the invention and their practical application so as to enable others skilled in the art to utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated.

Claims

CLAIMS What we claim:

1. A network for use in a vehicle, comprising: a bi-directional optical bus for carrying optical signals, the optical bus being placed within the vehicle; the bi-directional optical bus permitting optical signals to travel in both directions simultaneously along the optical bus; a plurality of units for performing at least one of transmitting optical signals onto or receiving optical signals from the bi-directional optical bus; a plurality of passive optical couplers with each optical coupler associated with a corresponding unit; the passive optical couplers and the plurality of units being contained within the vehicle; the optical couplers for: directing optical signals traveling along the bi-directional optical bus in either direction toward the corresponding unit; and directing optical signals from each unit onto the bi-directional optical bus in both directions; and an optical amplifier for amplifying the optical signals, the optical amplifier being located within the vehicle; the optical amplifier for performing amplification of the optical signals traveling in both directions; an engine system for at least monitoring operation of the vehicle, the engine system comprised of a first set of the units; and a second system comprised of a second set of the units; wherein the first set of units associated with the engine system and the second set of units associated with the second system are both coupled to the bi-directional optical bus and wherein the engine system and the second system are located within the vehicle.

2. The system as set forth in claim 1, further comprising the vehicle.

3. The system as set forth in claim 2, wherein the vehicle comprises a land vehicle.

4. The system as set forth in claim 2, wherein the vehicle comprises a sub-terrain vehicle.

The system as set forth in claim 2, wherein the vehicle comprises a water vehicle.

The system as set forth in claim 2, wherein the vehicle comprises an under-water vehicle.

7. The system as set forth in claim 2, wherein the vehicle comprises a space vehicle.

8. The system as set forth in claim 2, wherein the vehicle comprises an air vehicle.

9. The system as set forth in claim 1, wherein the engine system includes units for controlling operation of the vehicle.

10. The system as set forth in claim 1, wherein the second system comprises an entertainment system having units for producing audio to occupants of the vehicle.

11. The system as set forth in claim 1, wherein the second system comprises an entertainment system having units for displaying video to occupants of the vehicle.

12. The system as set forth in claim 1, wherein the second system comprises a data system.

13. The system as set forth in claim 1, wherein the second system comprises a communication system.

14. The system as set forth in claim 1, further comprising a third system and wherein the third system has a third set of units connected to the bi-directional optical bus.

15. A method of communicating within a vehicle, comprising: carrying optical signals along a bi-directional optical bus, the optical bus being placed within the vehicle; permitting the optical signals to travel in both directions simultaneously along the optical bus; providing a plurality of units within the vehicle; transmitting optical signals onto the bi-directional optical bus in both directions at a first set of units; receiving optical signals traveling in both directions along the optical bus at a second set of units; directing optical signals traveling along the bi-directional optical bus in either direction toward the corresponding unit; directing optical signals from each unit onto the bi-directional optical bus in both directions; and the optical amplifier for performing amplification of the optical signals traveling in both directions; providing an engine system with one group of the units; coupling units in the engine system to the bi-directional optical bus; monitoring operation of the vehicle with the engine system; providing a second system comprised of a second group of the units; and coupling units in the second system to the bi-directional optical bus.

16. The method of communication as set forth in claim 15, further comprising providing a third system comprised of a third group of units and coupling units in the third system to the bi-directional optical bus.

17. The method of communication as set forth in claim 15, further comprising controlling operation of the vehicle with the engine system