MOTOTRBO Link
MOTOTRBO Link is a feature/configuration in all SLR series repeaters that allows RF sites, in an IP Site Connect system, to be linked using backhaul repeaters. This is useful when the sites cannot be linked using leased line or microwave because of distance; practicality or obstructions. In this configuration, sites are linked together using separate repeaters and DMR channels that are solely used for linking the sites[1].
Typically, the repeaters in an IP Site Connect system would be linked together via microwave backhaul or some form of fixed line. In most cases, this is possible since the RF sites are within line of sight of each other (e.g. mountain-top to mountain-top) or the required infrastructure is present (e.g. telecom company has DSL or fiber at the location).
In a MOTOTRBO Link system, when a radio user initiates a voice or data call, the repeater receives the call and forwards it to the adjacent backhaul site(s) via the link repeater and channel. This call is, in turn, and repeated by the repeaters at all adjacent sites along the backhaul chain.
In the above diagram, Repeater 1 and Repeater 6 are standard repeaters used to provide radio service to users in that area. Repeaters 2-5 are link repeaters and are used to link Repeater1 and 6 - none provide radio service and hence can be in a different frequency band. To save space and energy, SLR1000s could be used for Repeater 2-5.
A custom sync cable (red) connects repeater 1 to 2; 3 to 4 and 5 to 6. Since each site only has two repeaters, the Ethernet switches are optional but aid in diagnosis and are there for any possible expansion. The SLR repeaters support autosense.
If the repeater site on the left (repeater 1 and 2) was within RF range of the repeater site on the right (Repeater 5 and 6), the middle site (Repeater 3 and 4) could be removed.
Although a mobile radio could - in theory - be used for linking sites, it does not have sufficient RF filtering and is therefore unsuitable for this application. In terms of reliability and RF filtering, well suited for this.[2] MOTOTRBO mobiles - or any mobile radio for that matter - cannot be used to link digital repeaters as the necessary signaling is not present on the accessory connector.
Origin Site
The Origin Site is the first repeater site in a backhaul chain. Only one origin site is supported in a MOTOTRBO Link system.
In the above diagram, repeater 1 and 2 would be the origin site though there is noting preventing repeater 5 and 6 performing this role (if repeater 5 & 6 were the origin, then repeater 1 & 2 would then have to be the terminating site).
IP Site Connect Beacons flow towards the origin site so that they can be aggregated by the proxy repeater, at the origin site. In a dedicated link configuration, the origin site must contain at least one link repeater and one standard repeater.
Interim Site
Interim sites are the repeater sites located between the origin site and the terminating sites in a backhaul chain of repeaters. Many interim sites are supported. In a dedicated link configuration, the interim sites must contain at least two link repeaters and an optional standard repeater.
In the above diagram, repeater 3 and 4 would be configured to operate as the interim site. A third repeater (optional) could be added at this site and could serve as a standard repeater providing radio service to users in that area.
Terminating Site
A terminating site is the repeater site at the end of a backhaul chain. A backhaul chain supports only one terminating site. Forks are not supported. The main fork that starts at the origin site of the backhaul chain is considered the first fork. A terminating site must have a standard repeater.
Repeater 5 and 6 would be the terminating site. As mentioned above, Repeater 1 and 2 could also be the terminating site - though this would mean that repeater 5 and 6 would have to be configured as the origin site.
Dedicated Link Repeater
Each site must contain at least two repeaters, one of which must be configured as a Dedicated Link repeater. This repeater is dedicated to linking two sites together by forwarding the call data between the adjacent site(s) in the chain. Since radio user will never access the channel used by this repeater, it can be in a different frequency band to the Standard Repeater(s).
Up to eight backhaul links (hops) can be created using this configuration. When used in conjunction with a Yagi-Uda or Corner-Reflector antenna, great distances can be achieved thus allowing repeaters, far away from each other, to be linked at a lower cost than microwave.
The following configurations are possible:
- With a Standalone Dedicated-Link Backhaul, the system consists of one MOTOTRBO Link chain, which consists of no more than nine MOTOTRBO Link sites.
- With a Hybrid Dedicated-Link Backhaul, the system consists of one IPSC Backhaul network and one or more standalone MOTOTRBO Link chains. In such a configuration there is a proxy repeater which bridges calls between the IPSC Backhaul network and the backhaul chain.
Standard Repeater
A Standard Repeater is a repeater that provides service to the radios within its coverage area. Voice or data calls placed on any site in the system will be retransmitted via this, and any other, Standard Repeaters in the system.
Within a backhaul site, the Standard and Dedicated Link repeaters are connected via ethernet. Additionally, the repeaters synchronize their TDMA bursts via a cable connected to the GPIO pins on the accessory connector. These GPIO pins are also configured for Site Slot Sync Input and Site Slot Sync Output.
Each backhaul site in the system should be treated as an isolated IP Site Connect system. This means that each site must have one Master repeater and the repeaters on that site must be in the same, unique IP subnet. Also, if the backhaul link goes down for any reason, each backhaul site continues to work as an isolated IP Site Connect system.
Radio Operation
The radio will only sound a talk permit tone when the call has been set up across the whole backhaul chain of repeaters. During a voice call sett up, the Standard Repeater transmits a Control Signaling Block (CSBK) to the radio requesting the call, confirming that it has the floor and may continue.
For data, the radio will access the channel without any confirmation. If this fails, it will retry several times before failing.
Since MOTOTRBO Link configuration uses daisy-chaining, each new site that is added to the chain increases the transmission delay required for a call to be transmitted from the origin of the chain to a terminating site in the chain. To enable a good user experience with minimal delay, a MOTOTRBO Link chain of repeaters is limited to chaining together up to nine sites with eight OTA links. And, MOTOTRBO Link systems are not expected to be heavily loaded systems with many users per site.
Limitations
A MOTOTRBO Link system supports all the standard IP Site Connect repeater mode features, with the following exceptions:
- Radios are able to roam between sites in a single link but not onto sites from another link or IPSC system.
- MOTOTRBO Link only supports Backhaul Channel Access (BCA) with a TRART mechanism as a channel access rule during call setup. This means that the TX Admit Criteria in the radio can only be set to Channel Free or Color Code Free.
- MOTOTRBO Link only supports RDAC presence and alarms from backhaul chain repeaters . No remote control via RDAC is possible.
- It is not possible to remotely program repeaters that are not connected to the Device Programmer via ethernet.
A MOTOTRBO Link system also does not support the following features:
- Transmit Interrupt
- Digital Telephone Patch
- Digital Voting
- Confirmed Group Data
- GPS Revert, Data Revert
- Enhanced/Scheduled GPS
- Repeater Call Monitoring
- CSBK Data
Hardware and Software Requirements
- SLR5000; SLR8000 or SLR1000 series repeaters with R02.09.00 firmware or newer. The MTR3000 and DR3000 (irrespective of memory size) do not support MOTOTRBO Link.
- A custom DB25-DB25 sync cable is required to connect repeaters at a site.
- Any DP/DM/SL/ION series radios with R02.09.00 firmware or newer. The first generation of MOTOTRBO radios will not support MOTOTRBO Link.
- Peripheral hardware for the repeaters such as duplexers, ethernet switches, and RF/Eth cabling.
- CPS 16.0 or later, otherwise Radio Management R2.9 or later.
Configuration Example 1[3]
The below tables show the repeater CPS settings for the following network. All other settings can be left at their details values.
Standard Repeater at Originating Site
| CPS Parameter | Location | Recommended Value |
|---|---|---|
| Radio Name | General Settings | As Required |
| Radio ID | General Settings | Must be unique |
| GPIO1 | Accessories | Site Slot Sync Input |
| Active Level GPIO1 | Accessories | Low |
| Ethernet IP | Network | Per the IP Plan |
| Gateway IP | Network | Per the IP Plan |
| Gateway Netmask | Network | Per the IP Plan |
| Link Type | Link Establishment | Master |
| Master IP | Link Establishment | Same as Ethernet IP above |
| Master UDP Port | Link Establishment | Usually 50000 |
| UDP Port | Link Establishment | Same as Master UDP Port above |
| Link Mode | MOTOTRBO Link | Dedicated Link |
| Site Type | MOTOTRBO Link | Origin Site |
| Repeater Type | MOTOTRBO Link | Standard Repeater |
| GPIO Timing Master | MOTOTRBO Link | Unchecked |
| Maximum number of links | MOTOTRBO Link | 1 |
| Link Beacon Interval | MOTOTRBO Link | 60 |
| IP Site Connect Link Site | MOTOTRBO Link | Unchecked |
| Channel Type | Zone | Digital |
| IP Site Connect (Repeater) | Digital Channel | Slot 1 & Slot 2 |
Link Repeater at Originating Site
| CPS Parameter | Location | Recommended Value |
|---|---|---|
| Radio Name | General Settings | As Required |
| Radio ID | General Settings | Must be unique |
| GPIO1 | Accessories | Site Slot Sync Output |
| Active Level GPIO1 | Accessories | Low |
| Ethernet IP | Network | Per the IP Plan |
| Gateway IP | Network | Per the IP Plan |
| Gateway Netmask | Network | Per the IP Plan |
| Link Type | Link Establishment | Peer |
| Master IP | Link Establishment | Same as Ethernet IP above |
| Master UDP Port | Link Establishment | Same as Master Repeater UDP Port in the Originating Site Standard Repeater |
| UDP Port | Link Establishment | Master UDP Port above + 1 |
| Link Mode | MOTOTRBO Link | Dedicated Link |
| Site Type | MOTOTRBO Link | Origin Site |
| Repeater Type | MOTOTRBO Link | Link Repeater |
| GPIO Timing Master | MOTOTRBO Link | Checked |
| Maximum number of links | MOTOTRBO Link | 1 |
| Link Beacon Interval | MOTOTRBO Link | 60 |
| IP Site Connect Link Site | MOTOTRBO Link | Unchecked |
| Channel Type | Zone | Digital |
| IP Site Connect (Repeater) | Digital Channel | Slot 1 & Slot 2 |
Link Repeater at an Interim Site
| CPS Parameter | Location | Recommended Value |
|---|---|---|
| Radio Name | General Settings | As Required |
| Radio ID | General Settings | Must be unique |
| GPIO1 | Accessories | Site Slot Sync Output |
| Active Level GPIO1 | Accessories | Low |
| Ethernet IP | Network | Per the IP Plan |
| Gateway IP | Network | Per the IP Plan |
| Gateway Netmask | Network | Per the IP Plan |
| Link Type | Link Establishment | Peer |
| Master IP | Link Establishment | Same as Ethernet IP above |
| Master UDP Port | Link Establishment | Same as Master Repeater UDP Port in the Interim Site Standard Repeater |
| UDP Port | Link Establishment | Above value + 1 |
| Link Mode | MOTOTRBO Link | Dedicated Link |
| Site Type | MOTOTRBO Link | Interim Site |
| Repeater Type | MOTOTRBO Link | Link Repeater |
| GPIO Timing Master | MOTOTRBO Link | Checked |
| Maximum number of links | MOTOTRBO Link | 1 |
| Link Beacon Interval | MOTOTRBO Link | 60 |
| IP Site Connect Link Site | MOTOTRBO Link | Unchecked |
| Channel Type | Zone | Digital |
| IP Site Connect (Repeater) | Digital Channel | Slot 1 & Slot 2 |
Standard Repeater at an Interim Site
| CPS Parameter | Location | Recommended Value |
|---|---|---|
| Radio Name | General Settings | As Required |
| Radio ID | General Settings | Must be unique |
| GPIO1 | Accessories | Site Slot Sync Input |
| Active Level GPIO1 | Accessories | Low |
| Ethernet IP | Network | Per the IP Plan |
| Gateway IP | Network | Per the IP Plan |
| Gateway Netmask | Network | Per the IP Plan |
| Link Type | Link Establishment | Master |
| Master IP | Link Establishment | Same as Ethernet IP above |
| Master UDP Port | Link Establishment | Usually 50000 |
| UDP Port | Link Establishment | Same as above |
| Link Mode | MOTOTRBO Link | Dedicated Link |
| Site Type | MOTOTRBO Link | Interim Site |
| Repeater Type | MOTOTRBO Link | Standard Repeater |
| GPIO Timing Master | MOTOTRBO Link | Unchecked |
| Maximum number of links | MOTOTRBO Link | 1 |
| Link Beacon Interval | MOTOTRBO Link | 60 |
| IP Site Connect Link Site | MOTOTRBO Link | Unchecked |
| Channel Type | Zone | Digital |
| IP Site Connect (Repeater) | Digital Channel | Slot 1 & Slot 2 |
Link Repeater at a Terminating Site
| CPS Parameter | Location | Recommended Value |
|---|---|---|
| Radio Name | General Settings | As Required |
| Radio ID | General Settings | Must be unique |
| GPIO1 | Accessories | Site Slot Sync Output |
| Active Level GPIO1 | Accessories | Low |
| Ethernet IP | Network | Per the IP Plan |
| Gateway IP | Network | Per the IP Plan |
| Gateway Netmask | Network | Per the IP Plan |
| Link Type | Link Establishment | Peer |
| Master IP | Link Establishment | Same as Ethernet IP above |
| Master UDP Port | Link Establishment | Same as Master Repeater UDP Port in the Terminating Site Standard Repeater |
| UDP Port | Link Establishment | Master UDP Port + 1 |
| Link Mode | MOTOTRBO Link | Dedicated Link |
| Site Type | MOTOTRBO Link | Terminating Site |
| Repeater Type | MOTOTRBO Link | Link Repeater |
| GPIO Timing Master | MOTOTRBO Link | Checked |
| Maximum number of links | MOTOTRBO Link | 1 |
| Link Beacon Interval | MOTOTRBO Link | 60 |
| IP Site Connect Link Site | MOTOTRBO Link | Unchecked |
| Channel Type | Zone | Digital |
| IP Site Connect (Repeater) | Digital Channel | Slot 1 & Slot 2 |
Standard Repeater at a Terminating Site
| CPS Parameter | Location | Recommended Value |
|---|---|---|
| Radio Name | General Settings | As Required |
| Radio ID | General Settings | Must be unique |
| GPIO1 | Accessories | Site Slot Sync Input |
| Active Level GPIO1 | Accessories | Low |
| Ethernet IP | Network | Per the IP Plan |
| Gateway IP | Network | Per the IP Plan |
| Gateway Netmask | Network | Per the IP Plan |
| Link Type | Link Establishment | Master |
| Master IP | Link Establishment | Same as Ethernet IP above |
| Master UDP Port | Link Establishment | Usually 50000 |
| UDP Port | Link Establishment | Same as above |
| Link Mode | MOTOTRBO Link | Dedicated Link |
| Site Type | MOTOTRBO Link | Terminating Site |
| Repeater Type | MOTOTRBO Link | Standard Repeater |
| GPIO Timing Master | MOTOTRBO Link | Unchecked |
| Maximum number of links | MOTOTRBO Link | 1 |
| Link Beacon Interval | MOTOTRBO Link | 60 |
| IP Site Connect Link Site | MOTOTRBO Link | Unchecked |
| Channel Type | Zone | Digital |
| IP Site Connect (Repeater) | Digital Channel | Slot 1 & Slot 2 |
Radios
Receive and transmit frequencies must correlate with those used in the repeater.
| CPS Parameter | Location | Recommended Value |
|---|---|---|
| IP Site Connect | Digital Channel(s) in Zone(s) | Checked |
| MOTOTRBO Link | Digital Channel(s) in Zone(s) | Checked |
| IP Site Connect | Digital Channel(s) in the Channel Pool | Checked |
| MOTOTRBO Link | Digital Channel(s) in the Channel Pool | Checked |
Custom Sync Cable for SLR5500[3]
| Standard Repeater | Link repeater | ||
|---|---|---|---|
| Pin | Function | Pin | Function |
| 2 | GPIO1 Site Slot Sync Input | 2 | GPIO1 Site Slot Sync Output |
| 9 | Ground | 9 | Ground |
NB! Shielded cable must be used.