Integrated Optics. Optical Components. Optoelectronic Transmitters. Optoelectronic Receivers.
Development of fibre optics
Fibre Amplifiers. Linear Semiconductor Optical Amplifiers. Silicon Lasers and Photonic Integrated Circuits. Di Liang, Alexander W. For a similar frame sync pulse transmitted at port , on the differential link in the opposite direction split site B to A , buffer is disabled by a high logic level at inverter and therefore blocks transmission of any input data at port Thus, the link extension circuitry in accordance with the present invention automatically configures itself either to transmit or receive and automatically ensures that there are no data collisions in an attempt to simultaneously transmit and receive from at either terminal in split site locations A and B.
The overall operation of the single site split location trunked communication system will now be described.
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The control switches in both split site locations A and B are set to select which site controller is in charge. Assume for the sake of explanation that site controller A is in charge of the split site system. The base stations A corresponding to radio channels are therefore controlled in the same fashion as described above and in more detail in U. The dispatch console at site location A participates in radio communications on channels in the same fashion as in a conventional single site trunk repeater system except that these local communications are routed through audio bridge A.
Moreover, monitored RF power from local base station transmitters is accomplished by the power monitor unit A with corresponding power signals being sent directly from the power monitor unit A to the site controller A. Dispatch console A can also participate in communications on remote channels located at split site location B. The T1 multiplexer A routes the audio through the audio bridge A to dispatch console A. Communications from dispatch console A are routed in the opposite path for transmission over channels Control signals between site controller A and remote base stations B will now be described.
Control channel information such as working channel requests from a base station to the site controller A , working channel assignments from the site controller A to the control channel base station and an available working channel base station, working channel confirmation and drop messages from the working channel base station to the site controller A are handled in two different scenarios.
Assume for the first scenario that one of the base stations A is designated as the control channel base station. Control messages such as those described above are sent from the site controller over line through the data switch to the control channel base station. That information is transmitted over the RF control channel via T1 multiplexer A , fiber optic communications link , T1 multiplexer B , and data switch B to base stations at split site location B.
Working channel assignments are communicated directly to remote base station from site controller A following a similar path.
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Status signals from the remote base stations B are routed to the site controller A through data switch B , T1 multiplexer B , communications link , T1 multiplexer A , and hardwire link As described above, power monitor unit A also receives detected RF power signals from power monitor unit B through the fiber optic link and multiplexing circuitry and routes the necessary power monitor information for base stations and split site locations A and B to site controller A.
If there becomes a need to operate the single site split location trunked radio communication system using site controller B, the control switches at each split site location would be switched accordingly so that the appropriate signal muting occurs. As described above, each of the base station trunking cards in the local and remote split site location are kept in loose synchronization via frame sync pulses sent out regularly by the control channel base station over the frame sync link FSL through the link extenders A and B over the frame sync link bus A significant advantage of the present invention is that the single site split location trunked radio communication system can operate as a single site in failsoft mode to continue trunking operations without a site controller in accordance with the procedures outlined in U.
Once the split location, single site trunking system enters a failsoft mode, the multiplexers in all of the trunking cards in base stations A and B automatically select port C, and the backup serial link BSL is activated. Trunking and other functions are then performed in a distributed fashion by the trunking cards with signals being communicated between the trunking cards via the BSL communications links and link extenders A and B. The control channel base station trunking card at one of the split site locations performs the supervisory role using various technique polling techniques to respond to working channel request messages and to assign base station working channels if available.
Accordingly, reliable single site split location trunked radio communications are ensured even if site controllers A and B are inoperable or if the system is intentionally operated without a site controller. Thus, the present invention provides a single site, split location trunked radio communication system that operates in a fashion which makes "transparent" the split nature of the system. Even though some of base stations are spaced a remote distance from the site controller, all of the base stations at both split sites can be accessed and assigned just as in the single site scenario.
This architecture is transparent because the single site split location system can be achieved without changing the hardware of existing base station transceivers, thinking cards, control and data buses, site controllers, or the radio units. Moreover, the various control and working channel protocols which have been established for a single site can be used without modification. The power monitoring operation for monitoring base station transmitter power in the split location, single site trunked radio communication system in accordance with the present invention will now be described in conjunction with the flow chart diagrams illustrated in FIGS.
The flow chart diagrams describe procedures followed by each power monitoring unit in both split site locations. The main power monitoring routine will first be described in conjunction with FIGS. System parameters are initialized in block including correlating base station channel numbers to the analog to digital input ports of A to D converter in each power monitoring unit PMU.
In step , the power monitoring unit checks the status of the signal from control switch and determines whether its local site controller is in charge of the entire split location, single site system decision block In decision block , a determination is made whether the power monitoring unit has received a request to measure the power of the currently active local base stations.
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If so, the power monitoring unit measures the transmit power for all local channels in block in accordance with the operations outlined in FIG. Control proceeds to decision block where the power monitoring unit determines whether or not it has received a request to measure remote power. If it has, the transmit power for remote base station transmitters currently transmitting is measured in block in accordance with the procedures outlined in FIG.
The power monitoring unit then determines whether or not a message has been received from the other power monitoring unit in decision block If so, the power monitoring unit reads the message received from the other PMU in block in accordance with the procedures outlined in FIG.
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Similarly, the power monitoring unit determines whether or not a message has been received from the site controller in decision block If it has, the message is read in block in accordance with the procedures outlined in FIG. At this completion of the power monitoring routine, control proceeds back via flag A to the beginning of the power monitor routine. The procedures for reading site controller messages referenced in block in FIG. The PMU inputs data from its site communications buffer in block and determines whether or not its site controller has been set as the master site controller by checking its MSC flag in block If the MSC flag equals zero, control return to the main power monitoring loop via flag A.
If the MSC flag is set to one, the power monitoring unit analyzes the input data to detect a synchronization character, decodes the message from the site controller, and forwards that message to the other PMU via the T1 multiplexers and fiber optic communication link in step A number of different messages may be received from the site controller.
For example, in block if a poll message is received and decoded, the PMU sends a current alarm status report to the site controller. This alarm report informs the site controller of any base station transmitters at local and remote locations which may be transmitting below a threshold power. In response to an enable mask message from the site controller, the PMU records which channels have been enabled by the site controller as active channels. In response to a power request message in block , the PMU sets appropriate parameters to measure channel power at each base station transmitter.
Thereafter, control returns to the main loop via flag A. A routine for reading messages from the other PMU i. In block , the PMU inputs data received via the communications link and T1 multiplexer After detecting a sync character associated with the received message, the PMU inputs and decodes the message from the remote PMU in block For example, in step , the PMU typically decodes a raw power message from the remote PMU which includes raw power values from the remote base station transmitters corresponding to remote channels.
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Thereafter, control returns to the main loop. A routine for actually measuring the power of local base station channels referred to in block of FIG. In block , a variable "n" is set equal to the number of available channels. In decision block , it is determined whether or not variable "n" equals zero. If so, all of the power measurements for active channels have been measured and those power measurements are sent on to the site controller in block with control thereafter returning to the main power monitor routine via flag A. Otherwise, a decision is made whether the current channel number should be checked based for example on whether it is an enabled channel as defined for example by the enable mask received from the site controller and on a power mask identifying those particular channels for which the site controller requests a power measurement.
If this particular channel should not be checked, the variable n is decremented in block and control returns to decision block Otherwise, that particular channel's transmit power is measured, compared to a minimum power threshold, and used to update an alarm status message report ultimately sent back to the site controller in block A routine for measuring the power of remote base station channels as indicated in block of FIG. In block , a variable "n" is set to the number of available channels. In decision block , it is determined whether variable n equals zero.
If so, all of the remote channel power measurements have been taken, and those power measurements are sent to the other PMU via the communications link and multiplexers with control returning thereafter via flag A to the main power monitor routine If n does not equal zero, a decision is made in block whether this channel should even be checked based on, for example, enable and power monitoring masks sent from the site controller via the other PMU.
If not, the variable n is decremented in block and control returns to block The base station transmitter power corresponding to that channel is measured, compared to a minimum threshold, and the alarm status for that channel updated in block Thus, the power monitoring routine in accordance with the present invention provides a mechanism by which a single site controller located at one site location can monitor RF transmitter power of base stations at that location as well as monitor RF power transmitted by base stations located at a remote split site location.
In particular, the power monitoring unit whose local site controller is the master site controller currently in charge of the split location, single site trunked communication system performs power monitoring tasks associated with its own base station transmitters as well as coordinates power monitoring messages to and raw power values from the remote power monitoring unit over the fiber optic communications link via T1 multiplexers In summary, even if a split site location is completely disabled through loss of power or intentional disruption, the remaining split site location s continues to function with only a loss in system capacity.
The ability to operate spacially separated base stations using only one site controller or no site controller in failsoft mode provides excellent protection against both manmade and natural disasters that can disable a specific split site location.
Even if the local site completely failed and was nonoperational, the remote split site would continue to function to maintain trunked communications. The architecture of the present invention also permits easy and inexpensive expansion of an existing trunked radio communication system.
Moreover, in the single site, split location trunked radio communication system of the present invention, all assets are fully utilized during normal operation in contrast to traditional main and backup systems which include fully redundant assets where the backup assets are not utilized during normal operation.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Effective date : Year of fee payment : 4. Year of fee payment : 8.
Year of fee payment : Base stations located at physically separate, remote locations are operated as a single site to permit trunked radio communications between portable radios located at those split sites. A first trunked RF communication site located at a first split site location includes plural first base stations, each first base station including a transceiver corresponding to an RF communications channel. The first site also includes a first site controller, connected to each of the first base stations, for assigning base station transceivers to radios requesting an RF communications channel.
A second trunked RF communications site is located at a second split site location remote from the first split site location and includes plural second base stations along with a second site controller. A communication link links the first and second split sites so that they function as a single site trunked radio communications system with one of the first and second site controllers assigning the first and second base station transceivers to radios requesting RF communications channels.
Base station transmitter power is measured at the split site locations and reported to the site controller currently in charge of the split location, single site trunked radio communications system. What is claimed is: 1. A single site, split location trunked radio communications system, comprising: plural portable radios;. The system in claim 1, further comprising: wherein one of the site controller receives monitored RF power information for all of the first and second base station transceivers from the one of the first and second power monitoring units.
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The system in claim 3, further comprising: a communications link linking the first and second trunked RF communications sites, the first and second power monitoring units communicating monitored RF power data over the communications link. The system in claim 4, wherein the first site controls the operation of the first and second base stations so that they operate as a single site and the first power monitoring unit receives monitored RF power data from the second power monitoring unit over the communications link.
The system in claim 3 wherein the first and second power monitoring units include: a data processor;.