Individual Link Options

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2. Individual Link Options

Since the firmware 1.6.2.0, RipEX radio improved the “Autospeed” function and added individual link options. RipEX radios can communicate with neighbouring RipEX units via different modulation rates, e.g. a central RipEX radio communicates with 10 remote radios and for each of those remote radios, it can configure individual modulation rate, FEC and ACK.

The only limitation of this feature is that all the frames have to have the same symbol rate and the same principle of modulation (i.e. CPFSK or linear).

Modulation types which can be combined within one approval type (FCC, CE or Narrow):

2CPFSK & 4CPFSK with or without FEC
  or
D2PSK & Pi/4DQPSK & D8PSK &16DEQAM with or without FEC

The following picture gives an example of a network layout. Let us assume, that all signals are strong enough to ensure almost perfect operation:

Topology

Fig. 2.1: Topology

In the following sections, all RipEX units will be configured and Flexible/BDP differences will be explained.

2.1. Flexible Protocol

Flexible protocol individual link options

Fig. 2.2: Flexible protocol individual link options

In Flexible protocol, each individual radio link can be configured with different settings (modulation rate, FEC, ACK). In the Figure 2.2 three radio links are configured, each with different settings.

NOTE:
Please see the Chapter 2.2. Base Driven Protocol for differences.

2.1.1. RipEX A Configuration

RipEX A Settings

Fig. 2.3: RipEX A Settings

The basic configuration is simple. Just edit the following parameters:

  • Unit name: RipEX A

  • Operating mode: Router

  • Radio IP: 10.10.10.1

  • Radio Mask: 255.255.255.0

  • TX/RX Frequency: 412.000.000 (used within this example)

  • Ethernet IP: 192.168.1.1

  • Ethernet Mask: 255.255.255.0

And after these changes, open Radio protocol details – e.g. click on the “Radio protocol” button. A new pop-up menu appears:

RipEX A (Base) Radio protocol details

Fig. 2.4: RipEX A (Base) Radio protocol details

  • Radio protocol: Flexible

  • Mode: CE

  • Modulation type: QAM

  • Modulation rate: 16DEQAM

  • FEC: Off

  • ACK: On

  • Retries: 3

Open the Advanced parameters “Individual link options” section and “Add” a new line.

  • Counterpart Radio IP: 10.10.10.4

  • Modulation rate: π/4DQPSK

  • FEC: On

  • ACK: On

  • Retries: 3

  • Note: RipEX D

This configuration makes 16DEQAM the default modulation (used for all radio links by default). FEC is disabled by default. The “Individual link options” line forces RipEX A to use π/4DQPSK modulation with enabled FEC for the radio link to RipEX D (10.10.10.4).

NOTE:
In Flexible protocol, modulation rate must be configured in all RipEX units. In BDP, modulation rates are controlled by the Base station configuration (remote units must comply with Modulation type only).

RipEX A Routing

Fig. 2.5: RipEX A Routing

Three routes are added – accessibility of all remote Ethernet subnets.

  • 192.168.2.0/24 via 10.10.10.2 (direct link)

  • 192.168.3.0/24 via 10.10.10.2 (RipEX B is used as a repeater)

  • 192.168.4.0/24 via 10.10.10.4 (direct link)

2.1.2. RipEX B Configuration

RipEX B Settings

Fig. 2.6: RipEX B Settings

Parameters different from RipEX A:

  • Unit name: RipEX B

  • Radio IP: 10.10.10.2

  • Ethernet IP: 192.168.2.1

Open the Radio protocol details:

RipEX B Radio protocol details

Fig. 2.7: RipEX B Radio protocol details

  • Radio protocol: Flexible

  • Mode: CE

  • Modulation type: QAM

  • Modulation rate: 16DEQAM

  • FEC: Off

  • ACK: On

  • Retries: 3

Default modulation rate is 16DEQAM (without FEC). Open the Advanced parameters “Individual link options” section and “Add” a new line.

  • Counterpart Radio IP: 10.10.10.3

  • Modulation rate: D8PSK

  • FEC: Off

  • ACK: On

  • Retries: 3

  • Note: RipEX C

RipEX B will always use D8PSK modulation rate (without FEC) when communicating with RipEX C (10.10.10.3). The opposite direction rate must be configured in RipEX C.

RipEX B Routing

Fig. 2.8: RipEX B Routing

Routing rules:

  • 192.168.1.0/24 via 10.10.10.1 (direct link)

  • 192.168.3.0/24 via 10.10.10.3 (direct link)

  • 192.168.4.0/24 via 10.10.10.1 (RipEX A is used as a repeater)

2.1.3. RipEX C Configuration

RipEX C Settings

Fig. 2.9: RipEX C Settings

Parameters different from RipEX A:

  • Unit name: RipEX C

  • Radio IP: 10.10.10.3

  • Ethernet IP: 192.168.3.1

Open the Radio protocol details:

RipEX C Radio protocol details

Fig. 2.10: RipEX C Radio protocol details

  • Radio protocol: Flexible

  • Mode: CE

  • Modulation type: QAM

  • Modulation rate: D8PSK

  • FEC: Off

  • ACK: On

  • Retries: 3

Default modulation rate is D8PSK (without FEC) and there is no special individual link option configured.

RipEX C Routing

Fig. 2.11: RipEX C Routing

RipEX C only configures a default route via RipEX B (10.10.10.2).

2.1.4. RipEX D Configuration

RipEX D Settings

Fig. 2.12: RipEX D Settings

Parameters different from RipEX A:

  • Unit name: RipEX D

  • Radio IP: 10.10.10.4

  • Ethernet IP: 192.168.4.1

Open the Radio protocol details:

RipEX D Radio protocol details

Fig. 2.13: RipEX D Radio protocol details

  • Radio protocol: Flexible

  • Mode: CE

  • Modulation type: QAM

  • Modulation rate: π/4DQPSK

  • FEC: On

  • ACK: On

  • Retries: 3

Default modulation rate is π/4DQPSK (with FEC) and there is no special individual link option configured.

RipEX D Routing

Fig. 2.14: RipEX D Routing

RipEX D configures only a default route via RipEX A (10.10.10.3).

2.1.5. Testing the Modulation Rate

One RSS ping can display all required information. Issue the RSS Ping from RipEX D (10.10.10.4) to RipEX C (10.10.10.3).

RSS ping from RipEX D to RipEX C

Fig. 2.15: RSS ping from RipEX D to RipEX C

The RSS ping output shows 3 radio hops in each direction, in total 6 radio hops. But the modulation rate is not visible here. Configure the Monitoring with correct parameters and Start it.

Monitoring Configuration

Fig. 2.16: Monitoring Configuration

Parameters:

  • Interface: Radio

  • Length: 0 Bytes

  • Port src: 8891, Include reverse checked

  • Protocol type: UDP

  • Headers: Radio Link

  • Promiscuous mode: On

  • Corrupted frames: unchecked

This configuration will monitor the Radio interface, displaying the required headers but no data (the payload is not important for this test). The RSS ping operates via UDP port 8891 and it’s not desired to display any corrupted packets. The promiscuous mode must be enabled so the monitoring displays all data within radio coverage; not only data destined to this radio (e.g. traffic from RipEX A to RipEX B).

Run the Monitoring by pressing the “Start” button and afterwards, re-run the RSS ping.

RSS Ping Monitoring output

Fig. 2.17: RSS Ping Monitoring output

For each displayed packet, there is information about Modulation rate and FEC. See the highlighted values “MC:XY”.

TX Modulation and Coding ((MC:00)) explanation:

  • [7..4] Modulation Select Nibble

    • 0x0 = 2-CPFSK (default)

    • 0x1 = 4-CPFSK

    • 0x8 = DPSK

    • 0x9 = π/4DQPSK

    • 0xA = 8DPSK

    • 0xB = 16-DEQAM

  • [3..0] Coding Select Nibble

    • 0x0 = FEC Off (default)

    • 0x1 = FEC On

In our example, there are three values:

  • MC:91 – π/4DQPSK & FEC On, used for the Radio link between RipEX D and RipEX A

  • MC:B0 – 16-DEQAM & FEC Off, used for the Radio link between RipEX A and RipEX B

  • MC:A0 – 8DPSK & FEC Off, used for the Radio link between RipEX B and RipEX C

The direction back is the same in our example. In Flexible mode, it is even possible to define different settings for different directions of one radio link. This is not possible in BDP.

Run RSS ping from another RipEX to any other and verify the behaviour in the Monitoring menu. You can check the same using any traffic, of course – e.g. run your application over the testing network.

2.2. Base Driven Protocol

Base Driven protocol – Individual link options

Fig. 2.18: Base Driven protocol – Individual link options

Base Driven protocol is slightly different in the way it handles individual link options. In BDP, all communication is strictly controlled by the Base station and this Base station configures all modulation rates within the whole network. Individual remote units must comply with the Modulation type; ACK can be configured at each remote unit separately.

In Figure 2.18 you can see two Modulation rates for one Radio link between RipEX A and RipEX B. This is due to BDP behaviour. If the Base station is communicating with RipEX B, it uses 16DEQAM modulation rate. But if it communicates with RipEX C, it uses 8DPSK for the whole path (i.e. for those two Radio hops and the way back as well). It is NOT possible to configure it as in the Flexible mode.

NOTE:
If there was another RipEX behind RipEX B (repeater), we could configure the communication via another Modulation rate, e.g. π/4DQPSK. And when communicating with this unit, the Radio hop between RipEX A and RipEX B will operate using this π/4DQPSK Modulation rate.

Another difference is that all the communication goes over the Base station. Even if we had a direct Radio link between RipEX D and RipEX C, the communication must go over the Base station (RipEX A).

See the following configuration example of how to configure the same network as in Chapter 2.1., but using BDP.

2.2.1. RipEX A Configuration

RipEX A Radio Protocol details

Fig. 2.19: RipEX A Radio Protocol details

Open the Radio protocol details of RipEX A (Base) and change the configuration:

  • Radio protocol: Base driven

  • Station type: Base

The Individual link options submenu disappeared, but a very important submenu “Remotes” has appeared and can be configured. All remote units must be configured in this table, otherwise they will not be accessible. Configure all three remote units:

  • Protocol address: 2

    • Modulation rate: 16DEQAM

    • FEC: Off

    • ACK/CTS: Enabled (3, 3)

    • Connection: Direct & Repeater

  • Protocol address: 3

    • Modulation rate: D8PSK

    • FEC: Off

    • ACK/CTS: Enabled (3, 3)

    • Connection: Behind Repeater

  • Protocol address: 4

    • Modulation rate: π/4DQPSK

    • FEC: On

    • ACK/CTS: Enabled (3, 3)

    • Connection: Direct

NOTE:
Please see the details in BDP application notes.

Different modulation rates are used for each remote station. If the Base communicates with Remote 3 (RipEX C, 10.10.10.3), it uses D8PSK for all radio links on its path (even for the link Base <-> RipEX2).

Important change must be done in the Routing menu as well.

RipEX A Routing

Fig. 2.20: RipEX A Routing

2.2.2. RipEX B, C and D Configurations

All the remote RipEX units have the same configuration. Change the Radio protocol to BDP and the station type to “remote”.

Remote RipEX Radio protocol details

Fig. 2.21: Remote RipEX Radio protocol details

In the Routing menu, configure only the default route to 10.10.10.1, because all the communication is routed over the Base station.

Remote RipEX Routing

Fig. 2.22: Remote RipEX Routing

2.2.3. Testing the Modulation Rate

The test will be the same – RSS ping from RipEX D to RipEX C.

RSS ping from RipEX D to RipEX C

Fig. 2.23: RSS ping from RipEX D to RipEX C

In BDP, only the last hop is displayed in path to/from the Base unit. I.e. there are only two hops displayed for each direction, instead of three.

RSS Ping Monitoring output

Fig. 2.24: RSS Ping Monitoring output

The first transmitted packet has the MC value 91 = π/4DQPSK with enabled FEC. The second displayed packet is from the Base station to RipEX B (repeater) and D8PSK modulation rate without FEC is used. A retransmitted packet from this repeater is also displayed using the same rate.

The RSS ping reply and a retransmitted packet both have the D8PSK rate as configured and the last hop uses π/4DQPSK again.

NOTE:
Please see the details in BDP application notes.