HK1119905A - Multimode land mobile radio - Google Patents

Description

Multi-mode land mobile radio

The present invention relates generally to land mobile radios, and more particularly to a land mobile radio that provides communication of land mobile radio content using a land mobile radio network or a cellular data network.

Land Mobile Radio (LMR) may be used to provide communication between different mobile units. Land mobile radio band communications, such as public safety radio communications (e.g., police, fire department, etc.), are typically available in the VHF, UHF, 700MHz, and 800MHz frequency bands. The Federal Communications Commission (FCC) allocates a portion of each of these frequency bands to public safety Communications services and refers to them as public safety frequency bands. These communications may also be provided using Private Land Mobile Radio Service (PLMRS).

Cellular networks may also provide communication between different mobile users, such as cellular telephones. These cellular networks, as well as LMR networks, are continuing to be enhanced and allow for improved operation and communication. For example, cellular networks currently provide Push-to-talk (ptt) services that allow direct connection capability. Thus, in a two-way radio or "walkie talkie" type communication, one cellular telephone user may request a direct-connect communication link with another cellular telephone user. As another example, cellular networks provide high-speed Data services, such as General Packet Radio Service (GPRS), Enhanced Data Rates for GSM Evolution (EDGE), Evolution Data Optimized (EV-DO), Universal Mobile Telephone Service (UMTS), and so on.

For example, known systems that provide enhanced services or features, such as improved call or voice features, that may be used for mission critical wireless applications, such as public safety applications, augment or replace conventional LMR systems with commercial cellular services, such as PTT services. These known systems are provided using specialized gateway equipment capable of achieving certain interoperability capabilities between LMR systems and cellular networks having capabilities such as PTT. Interoperability is provided by translating and/or converting data or voice communications to be communicated between networks, such as from an LMR network to a cellular network.

New technologies are also being provided in the LMR field, including the use of digital communication instead of analog communication. In addition, LMR systems are currently using packet switching instead of circuit switching, for example, the construction of LMR networks using Internet Protocol (IP) and Voice Over IP (VoIP) to achieve high scalability and high performance.

However, these improvements have also resulted in a need to support migration to new technologies. Moreover, interoperability between systems deployed by different LMR owners/operators, or between different cellular carriers, becomes increasingly important, particularly when different technologies are used in different systems. It is well known to utilize multi-mode terminal devices to facilitate migration and interoperability. In LMRs, these devices are commonly referred to as multimode radios, and in the cellular domain, these devices are commonly referred to as multimode phones.

The multi-mode terminal device enables intersystem roaming, particularly roaming from one network and/or technology to another without user intervention. These terminal devices change modes as the user roams between different systems provided using different technologies. In addition, components operating in multiple protocols and frequency bands may also be integrated into a single terminal device. For example, in a cellular region, a multimode phone may roam between TDMA and CDMA networks. In the LMR area, radios may roam between analog trunk systems and digital trunk systems.

Multimodal operation is provided through interconnection of the respective network infrastructures. Therefore, in order to provide transparency to users, gateway equipment may be used to connect various systems or networks. Known devices for communicating between different types of networks or systems use different communication components (e.g., hardware and software) that are each specifically configured for communication with a particular network or system. For each system or network, the functions and operations of the system or network are implemented using capabilities and protocols specific to that system or network. However, these systems are limited to the total available set of functions, as the functions and user interfaces available to the user depend on the system in which the terminal device has roamed.

Moreover, the functionality of one system may differ significantly from the functionality available on another system. In addition, some end-to-end services, such as end-to-end encryption, cannot be provided due to the incompatibility of these protocols. For voice communications, the use of a gateway interconnection system may incur degradation in voice quality due to the conversion of voice data from one format to another.

Thus, these systems may not only operate at unsatisfactory quality levels, but may also require additional controls and equipment to achieve interconnectivity, thereby increasing the complexity and overhead of the overall system.

A solution to the above problem is provided by a Land Mobile Radio (LMR) that provides the following configuration: includes an LMR communication portion configured to provide communication with an LMR network; and a cellular data network communication portion configured to provide communication with a cellular data network.

And a solution to the above problem is provided by a multimode terminal device provided with the following configuration: including land mobile radios and cellular radio modems.

A solution to the above-described problems is also provided by providing a method of communicating Land Mobile Radio (LMR) content using LMR equipment. The method includes configuring a land mobile radio to communicate LMR content using one of an LMR network and a cellular data network. When communicating using the cellular data network, the LMR content is encapsulated using a packet switching protocol.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

figure 1 is a block diagram of a Land Mobile Radio (LMR) communication system constructed in accordance with an exemplary embodiment of the invention.

Figure 2 is a block diagram of an LMR unit constructed in accordance with an exemplary embodiment of the invention.

Figure 3 is a block diagram illustrating the internal configuration of an LMR unit constructed in accordance with an exemplary embodiment of the present invention.

Figure 4 is a perspective view of an LMR unit illustrating an external configuration constructed in accordance with an exemplary embodiment of the present invention.

Figure 5 is a perspective view of an LMR unit illustrating an external configuration constructed in accordance with another exemplary embodiment of the present invention.

Figure 6 is a perspective view of an LMR unit illustrating an external configuration constructed in accordance with another exemplary embodiment of the present invention.

Figure 7 is a front view of an LMR unit illustrating an external configuration constructed in accordance with another exemplary embodiment of the present invention.

Fig. 8 is a block diagram illustrating a protocol stack in accordance with an exemplary embodiment of the present invention.

Figure 9 is a flowchart illustrating a method for controlling delivery of LMR content in an LMR communication system in accordance with an exemplary embodiment of the present invention.

Fig. 10 is a block diagram of a packet switching protocol interface constructed in accordance with an exemplary embodiment of the invention.

Figure 11 is a block diagram illustrating formatted LMR content in accordance with an exemplary embodiment of the present invention.

Figure 12 is a flowchart illustrating a method of selecting an operating mode of an LMR unit in accordance with an exemplary embodiment of the present invention.

Figure 13 is a flowchart illustrating a method for processing LMR content in accordance with an exemplary embodiment of the present invention.

Figure 14 is a block diagram of an LMR communication system constructed in accordance with an exemplary embodiment of the present invention illustrating the communication coverage area.

Figure 15 is a block diagram of an LMR communication system constructed in accordance with an exemplary embodiment of the present invention illustrating the flow of data.

Various embodiments of the present invention include a multimode terminal device having a Land Mobile Radio (LMR) unit that provides LMR content, such as LMR services, using both an LMR network and a cellular data network. The LMR content maintains the LMR application layer but is communicated over the cellular packet-switched data network using the cellular frequency band instead of using the LMR frequency band in accordance with the LMR transport protocol.

The multi-mode device is configured to provide intersystem roaming between, for example, an LMR system and a cellular system. Operation using a cellular system is typically provided by including a cellular radio modem in the LMR device and supporting LMR features through encapsulation and communication of LMR voice, data, and control information, utilizing an end-to-end packet switching protocol between the LMR device and the packet switching infrastructure.

In various embodiments, when using a cellular system for communication, the data services of the cellular system are used. The cellular radio modem provides data services between an application layer in the LMR device and a gateway bridging the LMR system or network and the cellular system or network. An end-to-end protocol between the multimode LMR device and the gateway utilizes encapsulation techniques to transport LMR voice and data services over the cellular data network. The processes and techniques for performing encapsulation and packet switched transmission may also be referred to as LMR over cellular protocols.

It should be noted that when reference is made herein to LMR content, this generally refers to any type or kind of LMR voice and/or data content, and may define specific LMR services, operations, controls, etc. For example, the LMR content may include, but is not limited to, voice data, emergency signal data, control data related to selecting a particular task group, LMR data communicated between the radio unit and the server, reprogramming data (e.g., software upgrade data), and the like.

Before describing an LMR unit in accordance with various embodiments of the present invention, a wireless communication system will first be described.

As shown in fig. 1, a wireless communication system, and more particularly, an LMR communication system 20, constructed in accordance with various embodiments of the present invention provides communication between a plurality of multimode devices, and more particularly, between a plurality of LMR units 22 or LMR terminals. Communication between the LMR units 22 is provided via either the LMR network 24 or the cellular data network 26. Each LMR unit 22 is configured to provide communication with, for example, other LMR units 22 using one of the LMR network 24 and the cellular data network 26. In particular, each of the LMR units 22 is configured to switch between one of the LMR network 24 and the cellular data network 26 based on, for example, available network, available bandwidth, coverage area, communication signal strength, etc. Alternatively, or in another embodiment, a handoff between one of the LMR network 24 and the cellular data network 26 is made based on the type or content of the communication. Thus, in addition to providing communication over the LMR network 24, the wireless data services of the cellular data network 26 may also be used to support communication and/or transport of LMR application layer protocols.

Various embodiments of the present invention enable end-to-end LMR services that are overlaid (overlaid) over cellular data networks 26, thereby allowing implementation of mission critical LMR systems, such as in the service areas of these cellular data networks 26. To provide this functionality and the communication of LMR content using the cellular data network 26, each LMR unit 22, such as an LMR radio, is configured with a cellular radio modem to allow for the operation of end-to-end LMR application layer protocols and services between the LMR unit 22 and the packet-switched LMR infrastructure.

More specifically, as shown in figure 2, the multimode device terminal equipment, illustrated as the LMR unit 22, includes a plurality of modules or components configured to provide communication via either the LMR network 24 or the cellular data network 26. In particular, the LMR unit 22 includes an LMR application module 30 connected to an LMR transmission module 32 for configuring voice and/or data for communication via the LMR network 24 (having one or more LMR base stations 46) using an LMR transmitter/receiver 34, which may be a stand-alone unit or provided as a signal transceiver (e.g., an LMR radio). The LMR application module 30, the LMR transmission module 32 and the LMR transmitter/receiver 34 generally define an LMR communication portion 40 of the LMR unit 22. The LMR unit 22 also includes an encapsulation module 36 for encapsulating voice and/or data for communication via the cellular data network 26 using a cellular radio modem 38. The LMR application module 30, encapsulation module 36, and cellular radio modem 38 generally define a cellular data network communication portion 42 of the LMR unit 22.

Specifically, as shown in FIG. 3, the LMR unit 22 includes an LMR communication portion 40 and a cellular data network communication portion 42, both of which are connected to a selector 43. The LMR communication portion 40, the cellular data network communication portion 42 and the selector 43 are also all connected to the processor 45. In addition, a memory 47 (e.g., RAM and/or ROM) and a display 246 are also coupled to the processor 45. The input/output 51 is connected to the processor 45 and the selector 43. The user interface 250 is connected to the processor 45.

During operation, the processor 45 is configured to control selection of either the LMR communication portion 40 or the cellular data network communication portion 42 using the selector 43, as described in greater detail herein. Processor 43 may access memory 47, for example, to retrieve user preferences or predefined operating parameters. Processor 47 may also receive input (e.g., commands) from a user via user interface 250, for example, to activate or select a function or operation. The input/output 51 may include various transmit and/or receive components for transmitting to and receiving from the LMR network 24 or the cellular data network 26 (shown in figure 2). The display 246 displays information, such as communication information, e.g., channel or network selection information, from the processor 45.

Additional or different components may be provided to the LMR unit 22. For example, a Global Positioning System (GPS) unit may be provided as part of the LMR unit 22 to determine the location of the LMR unit 22.

The LMR unit 22 may be configured to have different external configurations, for example, depending on the particular application for the LMR unit 22. Various embodiments for different external configurations of the LMR unit are illustrated in figures 4-7. It should be noted that the internal configuration of each LMR unit is the same as or similar to the configuration shown in figures 2 and 3. Modifications may be made, for example, to the size of memory 47 or display 246, or to the configuration of user interface 250. More specifically, for purposes of illustration, as shown in FIG. 4, the LMR unit 220 may be provided as a portable or removable unit having a housing 222 configured for handheld operation. The LMR unit 220 includes a power/volume button (knob)224 located at a top 228 of the LMR unit 220 to turn power on and off and to control volume. A system or channel button 226 located at the top 228 of the LMR unit 220 is provided to, for example, change the channels or talk groups in a particular network (e.g., the LMR network 24 or the cellular data network 26) and may have a predetermined number of rotational positions. An emergency button 230 and a selector button 232 may also be provided on the top 228. The panic button 230 is used to transmit emergency signals to other LMR units, which provide alerts to other units. Selector knob 232 is used to select a series or group of channels or talk groups. An antenna 234 extends from the top 228 to facilitate two-way communication with the LMR unit 220.

The side portion 236 of the LMR unit 220 also includes control components for controlling the operation of the LMR unit 220. In this embodiment, an options button 238, a clear/monitor button 240, and a push-to-talk button (PTT)242 are provided on the side portion 236. The option button 238 is used to select, for example, different options in a particular mode of operation (e.g., high/low power setting, keypad lock, display contrast, keypad illumination, etc.), and the clear/monitor button is used, for example, to clear a setting or end a call. The PTT button 244 is used to activate and deactivate PTT operations.

The front portion 244 of the LMR unit 220 generally includes a display 246, a speaker 248, a microphone 259, and a user interface 250. The user interface 250 includes a plurality of user-depressible buttons that may be used, for example, to enter numeric inputs and select various functions of the LMR unit 220. This part of the user interface may be configured as a keypad, for example. Additional control buttons, such as menu button 252, increase button 254, and decrease button 256 may also be provided accordingly. The increase button 252 and the decrease button 254 may be used to provide the same function as other user inputs, e.g., corresponding to the same operation as the system or channel button 226. The menu button 252 is used to access a stored menu and/or activate an item in a list displayed on the display 246.

For a plurality of user-depressible buttons corresponding to numeric inputs, each such user-depressible button may also provide control and activation of a particular function of the LMR unit 220. For example, the numeric button (1)258 may also be used to select a particular system or network, such as the LMR network 24 or the cellular data network 26 (shown in figures 1 and 2), which is switched accordingly between the LMR communication portion 40 and the cellular data network communication portion 42 (shown in figure 2). The numeric button (2)260 may also be used to select a specific user group, e.g., a predetermined user group on a particular system. The numeric button (3)262 may also be used to select a scan mode of operation for scanning channels in a particular system or network. The numeric button (4)264 may also be used to activate encryption, e.g., turn on and off a private encryption mode. The numeric button (6)266 may also be used to add a group or channel to be accessed by the LMR unit 220. The numeric button (7)268 may also be used to access the status of the LMR unit 220 or to provide the status of the LMR unit 220 to another LMR unit. The numeric button (8)270 may also be used to access a list of predetermined messages that can be transmitted by the LMR unit 220. The numeric button (9)272 may also be used to delete a selected group or channel of the currently selected system in the scan list. The numeric button (x) 274 may also be used to initiate interconnect calls with other units. The number button (#)276 is also used to initiate an individual (indivisual) call.

The display 246 may be configured with multiple rows, for example, to display system designations on one row, group designations on another row, or icons or other information (e.g., operating modes) on yet another row. Other information, such as a battery charge level indicator, may also be provided on the display 246.

The LMR unit 220 may also be referred to as a system unit. An LMR unit 280 configured as a scanning unit is depicted in figure 5. The same components as those shown in fig. 4 are denoted by the same numerals. The user interface 250 of the LMR unit 280 includes only the a/D button 282 to add or remove selected talkgroups or channels from the scan list of the currently selected system; SCN button 284 to turn on and off the scanning operation; and an OPT button 286 to activate one or more options.

Various other embodiments provide for the configuration of LMR units for different applications or for different settings. For example, the LMR unit 300 shown in fig. 6 may be configured (e.g., mounted on) for desktop or dashboard operation, and the LMR unit 310 shown in fig. 7 may be integrated in a dashboard 312, such as an automobile. Like numerals in fig. 6 and 7 correspond to like numerals in fig. 4 and 5.

The LMR unit may include additional components such as filters (not shown) such as a receive filter and a transmit filter for filtering signals received and transmitted by the LMR unit, respectively. For example, the LMR unit may also include a dedicated switch (not shown) or other controller for switching between the LMR communication portion 40 and the cellular data network communication portion 42 (shown in figure 2).

It should be noted that any of the various embodiments may be used below when referring to the LMR unit 22, including the LMR units 220, 280, 300, and 310.

During operation, the LMR system 20 may provide communication via the LMR network 24 using different known protocols, such as the LMR spatial link protocol. These LMR spatial link protocols include Project25(TIA 102) and ETSI TETRA standards, for example. These LMR spatial link protocols specify formats and procedures for the exchange of information between LMR units, such as the LMR unit 22, and the LMR network 24, and specifically the LMR base station 46. It should be noted that when one or more base stations 46 are part of a larger system, one or more of the base stations 46 are interconnected to switching equipment (not shown) that routes voice and data between different parts of the system to, for example, other LMR base stations or dispatch consoles

As is known, the LMR base station 46 processes, e.g., manipulates, the voice, data, and control information received over the spatial link into an alternative format suitable for communication within the LMR network 24, e.g., for transmission to switching equipment. For example, the received discrete voice, data, and control transmissions may be encapsulated in known TCP/IP or UDP/IP packets and the resulting IP packets communicated between one or more LMR base stations 46 and the switching equipment over the IP network.

The LMR unit 22 may also provide communication via the cellular data network 26 using different known protocols such as General Packet Radio Service (GPRS), enhanced data rates for GSM evolution (EDGE), evolution data optimized (EV-DO), Universal Mobile Telephone Service (UMTS), and the 802.16 standard. These cellular protocols specify the format and procedures for information exchange between the LMR unit 22, and in particular, the cellular radio modem 38 and the cellular data network 26.

For example, a cellular tower (not shown) having a base station (not shown) may be provided for receiving and processing signals from the LMR unit 22, e.g., to manipulate received voice, data and control information into an alternative format suitable for communication in the cellular data network 26, e.g., for transmission to a router or server (not shown) based on the IP address of the received data packets. For example, the received, encapsulated signal is de-encapsulated and appropriately routed in the cellular data network 26.

Thus, communication of data from either the LMR network 24 or the cellular data network 26 to the packet switched LMR infrastructure 41 is provided. It should be noted that the LMR content and LMR network may be configured according to different spatial link protocols. To provide for communication via either the LMR network 24 or the cellular data network 26 using the LMR unit 22, the communication protocol stack for communicating with each of these networks is partitioned as shown in figure 8. In particular, the LMR protocol stack 60 is partitioned into multiple layers for communication with the LMR unit 22 using the LMR network 24, which in one exemplary embodiment is a two-layer protocol stack having an LMR application layer 62 and an LMR transport layer 64. For example, an LMR application layer 62 and an LMR transport layer 64 may be provided by the LMR application module 30 and the LMR transport module 32, respectively (both shown in figure 2). The LMR application layer 62 is configured to provide interpretation and processing of voice, data and control information. The LMR transport layer 64 is configured to provide for the delivery of voice, data and control information over a transmission medium. As described herein, the LMR spatial link protocol defines both an LMR application layer 62 and an LMR transport layer 64.

In this two-layer protocol stack model, the LMR base station 46 (shown in figure 2) and switching equipment in the LMR network 24 (shown in figure 2) receive content from the LMR communication portion 40 (shown in figure 2) and communicate the LMR application layer 62 content therebetween via different transport layers. Specifically, as shown in figure 3, the LMR application layer 62 content is encapsulated at the LMR base station 46 (shown in figure 2) using LMR content encapsulation 66, as is known. In an exemplary embodiment, discrete transmission units are encapsulated in a transport datagram, and in particular, in a packet-switched transport datagram 68 that is communicated using a transport protocol. When the encapsulated datagram is received, the application layer content may then be restored, and in particular, the encapsulation of the application layer content may be undone.

In addition, this two-layer protocol stack model enables the delivery of LMR application layer services over non-LMR wireless networks using, for example, the cellular data network communication portion 42 (shown in figure 2). In particular, the cellular data network communication portion 42 is configured to provide an LMR application layer 62, but instead of using an LMR transport layer 64, transport services of the wireless cellular data network 26 (shown in figure 2) are used. In particular, the LMR encapsulation layer 70 is used with the packet-switched transport datagrams 68 so that the wireless cellular data network 26 communicates with the switching equipment using an appropriate transport protocol, whereby equivalent LMR application layer services can be delivered as the LMR communication portion 40. In particular, the packet-switched LMR infrastructure 41 (shown in figure 2) communicates LMR application services using LMR application layer switching 72 in conjunction with packet-switched transport datagrams 68.

It should be noted that the various embodiments are not limited to a two-layer protocol stack, and additional layers may be provided to a multi-layer protocol stack as desired or needed. For example, different session layers may be provided, such as a bulk (bulk) encryption layer. In addition, for example, an RTP layer may also be provided.

Various embodiments of the present invention provide for controlling the communication of LMR content in an LMR communication system using an LMR network and a non-LMR wireless network, in particular, a wireless cellular data network. In particular, a method 100 of controlling the delivery of LMR content is depicted in figure 9 and includes determining a network to be used to deliver the LMR content at 102. In an exemplary embodiment, it is determined whether to communicate LMR content using an LMR network or a cellular data network. This determination may be based on a manual selection, for example, a user input selection of which network to use. For example, a button or switch (shown in FIG. 2) on the LMR unit 22 may be used to make the selection. Alternatively or additionally, it may be automatically determined which network is to be used. For example, the network for communicating the LMR content may be selected based on the amount of data traffic or available bandwidth on a particular network, transmission priority, type of communication or content (e.g., voice or emergency broadcast signals, emergency communication or PTT requests), signal strength of the LMR unit, geographic location of the LMR unit, user preferences, etc. The operation and selection of a network to be used when communicating with the LMR unit will be described in more detail below in conjunction with figure 12.

After the network to be used for communicating the LMR content is determined at 102, a communication method is selected at 104 based on the determined network to be used. For example, the rate or baud rate of the communication may be selected (manually or automatically) from a range of communication data rates. In addition, a setup (setup) procedure to establish and connect to the determined network may also be selected. For example, if an LMR network is to be used, an LMR communication setup routine may be performed in which a communication link is established between the LMR unit and the LMR network via an LMR transmitter/receiver in the LMR unit. If a cellular data network is to be used, a cellular data network communication setup routine may be performed in which a communication link is established between the LMR unit and the cellular data network via a cellular radio modem of the LMR unit. The setup routine may comprise any known suitable process for establishing a wireless communication link.

Next, at 106, LMR content is configured for delivery in accordance with the determined network and the selected communication method. For example, if the LMR content is to be communicated using the LMR network, a particular LMR standard in which the LMR content is configured or formatted is selected. In particular, an LMR standard is selected in which voice and/or data payloads defining LMR content are configured. This may include, for example, selecting one of Project25(TIA 102) or ETSI TETRA criteria for the communication method. In addition, for example, a proprietary format may also be selected, such as the OpenSky M/A-CO proprietary format, the Networkfirst, or the EDACS system proprietary format.

Additionally, for example, if the LMR content is to be communicated using a cellular data network, a particular wireless cellular data network standard in which the LMR content is configured or formatted is selected. Specifically, a wireless cellular standard is selected in which voice and/or data payloads defining LMR content are configured. This may include, for example, selecting one of General Packet Radio Services (GPRs), enhanced data rates for GSM evolution (EDGE), evolution data optimized (EV-DO), Universal Mobile Telephone Service (UMTS), or 802.11 system standards.

Additionally, as described in more detail above in connection with figure 8, a specific protocol stack may be used depending on the network to be used to communicate the LMR content. Also, if the LMR content is to be communicated using the LMR network, an LMR protocol header is added to the LMR data payload. If the LMR content is to be communicated using the cellular data network, a packet switching protocol header is added. As described in more detail below, if the LMR content is to be communicated using the cellular data network, the LMR content is encapsulated, for example, using an IP to encapsulate the encapsulated Internet Protocol (IP) prior to communication to or from the cellular data network. Hereinafter, a method of encapsulating data will be described in more detail with reference to fig. 13.

Referring again to figure 9, after the LMR content is configured at 106, the configured LMR content is communicated at 108. For example, if the LMR content is configured to be communicated using the LMR network, the LMR content may be communicated using an LMR transmitter and receiver. If the LMR content is configured to be communicated using a cellular data network, the LMR content may be communicated using a cellular radio modem. It should be noted that a cellular radio modem may be configured to operate in a single mode of operation, or it may be configured to operate in multiple modes. In another embodiment, more than one cellular radio modem may be provided, each of which may be configured to operate in a single mode of operation or may be configured to operate in multiple modes.

After the LMR content is communicated and received, for example, by a base station of the network, the LMR content is processed to determine an action at 110. This may include, for example, determining whether to communicate voice data or to issue an emergency signal or PTT request to the talk group. For example, if the LMR content is communicated using a cellular data network, the destination address of the encapsulated datagram may first be determined and then communicated to the location for processing using a router in the network.

Referring now to fig. 10 and another embodiment of the present invention, the packet switched protocol interface 120 may be provided in conjunction with the cellular data network 26 (shown in fig. 2), for example, the packet switched protocol interface 120 may be provided as a separate unit (e.g., a separate module), a card for connecting to a server in the cellular data network, or software for downloading to a server in the cellular data network. The packet-switched protocol interface 120 includes a processor 122, the processor 122 being configured to process the received packet-switched encapsulated LMR content for communication, such as to the packet-switched LMR infrastructure 41 (depicted in figure 2). In particular, as described in more detail herein, the processor may receive LMR content formatted as shown in figure 11. The LMR content typically includes an LMR data portion and a packet switching protocol encapsulation portion. In particular, the LMR content 130 may include a packet switching protocol header 132, an LMR protocol header 134, and LMR data 136, such as an LMR data payload.

This LMR content 130 is substantially encapsulated, for example, in an IP wrapper (wrapper). The processor 122 decapsulates the LMR content 130, for example, by removing the packet switching protocol header 132, and may store the decapsulated LMR content 130 in the memory 124. The LMR content 130 may then be further processed by the processor 122 to determine an action to perform or an address in the packet switched LMR infrastructure to which the LMR content 130 is to be communicated. Essentially, once the 130 encapsulation of the LMR content is removed, the LMR content 130 is configured for communication in a packet switched LMR infrastructure or LMR network. Control of the delivery of the LMR content 130 is controlled by a controller 126, wherein the controller 126 may include a router 128 for routing the LMR content 130 to a destination in the LMR network, for example. It should be noted that the LMR content may be repackaged (re encapsulated) for transmission in the LMR network or in the cellular data network.

The operation and selection of a network to be used by the LMR unit, and more particularly, the selection of an LMR network or a non-LMR network, such as a cellular data network, that communicates LMR content will now be described. In general, the LMR unit may automatically select a network to be used based on, for example, user settings, predetermined settings, user defined settings, the operating conditions of the LMR unit, etc. System selection may also be made by the user using a selector or input on the LMR unit. A method 350 for selecting the operating mode of the LMR unit, and more particularly, a method for determining when to use a particular network for communication is described in figure 12. Specifically, at 352, the current network or communication system being used is determined. Then, at 354, the operating conditions of the LMR unit are determined. This may include, for example, the current signal strength, the current geographic location, etc. Next, at 356, any user input or preference for a particular network is determined. For example, the user may enter specific network preferences based on geographic area, such as a preference to use the LMR network in areas where the user knows that cellular data network coverage is weak, or alternatively, a preference to use the cellular data network where the user knows that there is no LMR network coverage. For example, the user preferences may also be: the cellular data network is always used first if it is available. The input may also be based on a manual user selection of the LMR network or the cellular data network using a button or selector on the LMR unit.

Thereafter, at 358, the settings of the LMR unit are determined. This may include, for example, determining preprogrammed settings or preferences for the LMR unit, e.g., based on a threshold level of data traffic on a particular network or bandwidth available on the network, transmission priority, type of communication or content, etc. (e.g., voice or emergency broadcast signals, emergency communication or PTT requests), current network to be used for communication, etc. Then, at 360, it is determined whether the LMR settings override (override) user input or preference, or vice versa. For example, the LMR unit may be configured as follows: the emergency broadcast message must be transmitted over the LMR network and this overrides any user input or preference. If the LMR settings do not override the user input or preferences, then a network for communication is selected at 362 based on the user input or preferences and a corresponding communication portion of the LMR unit, such as the LMR communication portion 40 of the LMR unit 22 or the cellular data network communication portion 42 of the LMR unit 22 (all shown in FIG. 2), is accessed. This may also include using the determined operating conditions of the LMR unit to make the selection.

If it is determined at 360 that the LMR settings override the user input or preference, then at 364, a network for communication is selected in accordance with the LMR settings. This may also include using the determined operating conditions of the LMR unit to make the selection. It should be noted that the selection of the network to be used at 362 or 364 may result in the selection of a new network, or no change in network (i.e., continuing to use the network currently being used for communication). Additionally, after the network is selected at 362 or 364, if the network is changed, an indication may be provided at 366, such as an audible indication (e.g., an audible sound) or a visual indication (e.g., an LED on an LMR unit that is lit or a network selection displayed on a display).

For example, the method 350 may be performed periodically or upon certain events, such as user input, a change in the operating condition of the LMR unit, which may include exceeding a predetermined threshold, etc.

Referring now to figure 13 and a method 150 for processing LMR content, at 152, it is determined whether the LMR content is to be communicated using the LMR network. If it is determined at 152 that the LMR content is to be communicated using the LMR network, the LMR content is communicated to the LMR network at 154. This may include communicating the LMR content to a base station of the LMR network according to an LMR protocol header provided in connection with the LMR content. Next, the LMR content is encapsulated at 156, for example in a wrapper defined by the spatial link protocol described herein, and routed accordingly at 158. For example, the encapsulated LMR content, which may be configured as datagrams, may be routed in a packet switched LMR infrastructure.

At the destination of the LMR content, the LMR content is processed, e.g., de-encapsulated, at 160, and then an action is determined from the processed data at 162. For example, it may be determined at 162 that an emergency signal is to be sent, or that the LMR content is to be further routed to another base station. A corresponding action is then performed at 164, for example, in the packet switched LMR infrastructure.

If it is determined at 152 that the LMR content is not to be communicated using the LMR network, the LMR content is encapsulated for communication at 166. For example, in the exemplary embodiment, the LMR encapsulation module 36 (shown in figure 2) implements an LMR encapsulation layer 70 (shown in figure 8) to encapsulate the LMR content in a wrapper, such as an IP wrapper. The encapsulated LMR content is then communicated using the cellular data network at 168. This may include routing the encapsulated LMR content in the cellular data network at 170. Next, at 172, the LMR content is delivered to the packet switched infrastructure, e.g., based on the IP address from the IP package.

The LMR content is then processed at the destination, which may include decapsulating the LMR content and determining an action at 162. For example, it may be determined to send an emergency signal or to further route the LMR content to another base station. A corresponding action is then performed at 164, for example, in the packet switched LMR infrastructure.

Accordingly, various embodiments of the present invention provide for communicating LMR content using an LMR network or a non-LMR network, such as a cellular data network. If the LMR content is communicated using a cellular data network, the LMR content is encapsulated in a packet-switched protocol prior to transmission. For example, as shown in figure 14, an LMR communication system 200 generally includes a plurality of cellular data network base stations 202 and a plurality of LMR network base stations 204. Each of the plurality of cellular data network base stations 202 and the plurality of LMR network base stations 204 has a cellular data network communication coverage area 206 and an LMR network communication coverage area 208, respectively. In some locations, the cellular data network communication coverage area 206 and the LMR network communication coverage area 208 may overlap. Various embodiments of the present invention described herein allow an LMR unit 210, such as an LMR radio in a mobile unit or vehicle, to communicate via a cellular data network or an LMR network depending, for example, on the location of the LMR unit 210 and the corresponding available coverage area. More specifically, communication towers (not shown) corresponding to each of the plurality of cellular data network base stations 202 and each of the plurality of LMR network base stations 204 allow for wireless communication as described herein.

Additionally, as shown in figure 15, the controller 212 in the packet-switched LMR infrastructure 41 may be configured to control communications from the plurality of cellular data network base stations 202 and the plurality of LMR network base stations 204 described herein. The controller may process data packets received from the LMR network 24 and/or the cellular data network 26 to determine the appropriate action or routing procedure for the particular data packet described herein.

The various embodiments or components, such as the LMR communication system 20 or a controller therein, the LMR unit or a controller therein may be implemented as part of one or more computer systems, which may be separate from or integrated with the LMR communication system 20 or LMR unit. The computer system may comprise a computer, an input device, a display unit and an interface, for example, for accessing the internet. The computer may include a microprocessor. The microprocessor may be connected to a communication bus. The computer may also include a memory (memory). The memory may include Random Access Memory (RAM) and Read Only Memory (ROM). The computer system may also include a storage device, which may be a hard disk drive; or a removable external memory device such as a floppy disk drive, optical disk drive, etc. The external memory device may also be other similar mechanisms for loading computer programs or other instructions into the computer system.

As used herein, the term "computer" may include any processor-based or microprocessor-based system including systems using microcontrollers, Reduced Instruction Set Circuits (RISC), Application Specific Integrated Circuits (ASICs), logic circuits, and any other circuit or processor capable of executing the functions described herein. The above examples are illustrative only, and are thus not intended to limit in any way the definition and/or meaning of the term "computer".

The computer system executes a set of instructions stored in one or more storage elements to process input data. The storage element may also store data or other information as desired or needed. The storage element may be in the form of an information source or a physical memory element in the processing machine.

The set of instructions may include various commands that instruct the computer as a processing machine to perform specific operations such as the methods and processes of the various embodiments of the invention. The set of instructions may be in the form of a software program. The software may be in various forms such as system software or application software. In addition, the software may be in the form of a stand-alone collection of programs, a program module within a larger program, or a portion of a program module. The software may also include modular programming in the form of object-oriented programming. The processing of input data by the processing machine may be in response to a user command, or in response to a previous processing result, or in response to a request made by another processing machine.

As used herein, the terms "software" and "firmware" are interchangeable, and can include any computer program stored in memory for execution by a computer, including RAM memory, ROM memory, EPROM memory, EEPROM memory, and non-volatile RAM (NVRAM) memory. The above memory types are exemplary only, and are thus not intended to limit the types of memory usable for storage of a computer program.

It should also be noted that various embodiments of the present invention may also provide different and/or additional functionality. For example, end-to-end encryption may be performed, thus eliminating the use of intervening (interfacing) encryption equipment and the security risks encountered by owning such intervening equipment with access to the encryption key. In addition, various embodiments of the present invention may also provide end-to-end digital voice coding, thereby eliminating the use of intervening transcoding equipment, and thus eliminating the fidelity loss problems encountered when converting one digital voice format to another.

In addition, various embodiments of the present invention may also provide mission critical functions such as PTT, scanning, preemptive priority calls, emergency alerts and notifications, content scanning and tracking, navigation, dispatch, and GPS location. Mission critical functions may be implemented in different mission critical applications including, but not limited to, public safety, utilities, and public transportation.

Thus, the various embodiments provide for multi-mode operation that allows the same features, functions, and user interface to be implemented independent of the system (e.g., LMR network or cellular network) on which the LMR unit is operating. The various embodiments also allow for end-to-end encryption between LMR devices across different systems. In addition, encoding and re-encoding of the voice content is eliminated, thereby preserving voice quality.

Claims (21)

1. A Land Mobile Radio (LMR) (22), comprising:

an LMR communication portion (40) configured to provide communication with an LRM network (24); and

a cellular data network communication portion (42) configured to provide communication with a cellular data network (26).

2. An LMR in accordance with claim 1 wherein the cellular data network communication portion (42) comprises a cellular radio modem (38).

3. An LMR in accordance with claim 1 wherein said LMR communication portion (40) is configured to communicate using an LMR protocol and said cellular data network communication portion (42) is configured to communicate using an LMR-over-cellular protocol.

4. An LMR in accordance with claim 3 wherein the LMR over cellular protocol comprises a packet switched protocol.

5. An LMR in accordance with claim 1 further comprising a user interface (250) configured to receive a user input to select one of the LMR communication portion (40) and the cellular data network communication portion (42) for communication of LMR content (130).

6. An LMR in accordance with claim 1 further comprising a processor (45) configured to automatically select one of the LMR communication portion (40) and the cellular data network communication portion (42) for communication of LMR content (130).

7. An LMR in accordance with claim 1 further comprising a processor (45) configured to automatically select one of the LMR communication portion (40) and the cellular data network communication portion (42) for communication of LMR content (130) based on at least one of an operating condition, a user setting, and a predetermined setting.

8. An LMR in accordance with claim 1 further comprising a display (246) configured to identify the selected communication network.

9. An LMR in accordance with claim 1 further comprising a housing (222) having an LMR communication portion (40) and a cellular data network communication portion (42) therein and configured to provide handheld operation.

10. An LMR in accordance with claim 1 further comprising a housing having an LMR communication portion (40) and a cellular data network communication portion (42) therein and configured in a desktop or dashboard (312) operating configuration.

11. An LMR in accordance with claim 1 wherein the processor (45) is configured to encapsulate LMR content (130) using a packet switching protocol when communicating using the cellular data network communication portion (42).

12. An LMR in accordance with claim 1 wherein the processor (45) is configured to allow at least one of end-to-end encryption and end-to-end digital encoding with at least one other LMR unit (22).

13. A multimode terminal device comprising:

a land mobile radio (22); and

a cellular radio modem (38).

14. A multimode terminal device in accordance with claim 13 wherein said land mobile radio (22) is configured to communicate LMR content (130) using LMR protocols and said cellular data modem (38) is configured to communicate LMR content (130) using LMR-over-cellular protocols.

15. A multimode terminal device in accordance with claim 14 wherein the LMR-over-cellular protocol comprises a packet-switched protocol and further comprising an LMR encapsulation module (36) configured to encapsulate LMR content using the packet-switched protocol when communicating using a cellular radio modem (38).

16. A multimode terminal device in accordance with claim 13 wherein said land mobile radio is configured to communicate LMR content (130) using one of Project25(TIA 102), ETSI TETRA space link protocol, OpenSky M/N-COM specific format, NetworkFirst, and EDACS system specific format.

17. A multimode terminal device in accordance with claim 13 wherein said cellular radio modem is configured to communicate LMR content (130) using one of General Packet Radio Service (GPRS), enhanced data rates for GSM evolution (EDGE), evolution data optimized (EV-DO), and Universal Mobile Telephone Service (UMTS) and 802.11 system standards.

18. A multimode terminal device in accordance with claim 13 further comprising a processor (45) configured to automatically select one of the land mobile radio (22) and the cellular radio modem (38) for delivery of LMR content (130) based on at least one of an operating condition, a user setting, and a predetermined setting.

19. A multimode terminal device in accordance with claim 13 further comprising a user interface (250) configured to receive a user input to select one of a land mobile radio (22) and a cellular radio modem (38) for delivery of LMR content (130).

20. A method of communicating Land Mobile Radio (LMR) content (130) using an LMR device (22), the method comprising:

the land mobile radio (22) is configured to communicate LMR content (130) using one of the LMR network (24) and the cellular data network (26), the LMR content (130) being encapsulated using a packet-switched protocol when communicating using the cellular data network (26).

21. A Land Mobile Radio (LMR), comprising:

a cellular radio modem (38); and

an LMR encapsulation module (36) for encapsulating LMR content (130) for communication via the cellular radio modem (38).