MM8108-MF15457 Development and doubts

Projects
1

We are planning to use the Wi-Fi HaLow module MM8108-MF15457 and have already started our design activities. We are excited to work with this module and would appreciate technical support and guidance from your side.

We are developing a smart parking management system, where each unit managing a parking slot will transmit JPEG images along with diagnostic data to our backend servers.

Our plan is to deploy these units using Wi-Fi HaLow STA modules, connecting either to commercially available outdoor access points or to a custom-built access point.

The deployment environment will be typical outdoor parking areas with obstacles such as buildings, trees, and vehicles. Could you please advise on the realistic communication range we can expect under such conditions?

Additionally:

  • We are considering building a custom access point integrated with an LTE modem for backhaul connectivity. Is this architecture feasible?

  • Do you provide technical support for hardware bring-up and software integration for this module?

We look forward to your guidance.

2

Hi @HarshithG,

HaLow network with LTE backhaul is a sensible layout/usecase.

For support for hardware/software, there is this forum and the documentation/reference designs available in the customer portal on our website. Otherwise if further resources/assistance is needed, it can be organized by reaching out to our sales team via email.

4

No worries @HarshithG,

JPEG and some diagnostic data is very doable.

What is the expected practical throughput vs range for this module in outdoor environments with obstacles (vehicles, trees, buildings)

Throughput you can grab an estimate from our Rate vs Range estimator. It compares to LoRa but it will give you a rough estimate based on our testing in various environments. This will be very implementation dependent, eg if the device is installed with decent LOS to the AP you’ll get much better throughput than if it were to be occluded by the subject vehicle relative to the AP.

Are there any reference designs available for AP mode, especially for a setup involving multiple STA devices?

With HaLow it’ll be similar to setting up a standard Wi-Fi network. You can look at our EKH01

Do you have any recommended configuration (RAW / scheduling) for handling multiple nodes transmitting image data?

You’ll definitely want to look into scheduling as having a thundering herd can tank your network performance.

Since LTE and HaLow will be on the same device, you should consider how you’re handling the uplink. In many countries and regions, HaLow and LTE are in the same spectral neighborhood, meaning the LTE transmission will interfere with your HaLow transmission if they’re happening simultaneously on the same device. To alleviate this you’ll want something like a ‘wait/backoff’ period between STAs sending data to give the AP time to transmit what it’s received over LTE.

Is there any reference implementation for integrating HaLow AP with LTE backhaul (e.g., OpenWRT or embedded Linux)?

None that we provide, however with OpenWRT/Linux, if the LTE modem is supported you’ll use its network interface as the backhaul much like you would with a standard 2.4GHz/Ethernet backhaul.

With regards to our support team, based of your username, they’ve received your email as of yesterday, so you are in queue for them to respond to.

6

20 feet is relatively low, there’s a lot of potential issues ranging from hardware issues, eg the antennas’ radiation patterns not encompassing the devices, incorrect antennas, other interferes, software configuration, board design, general obstructions, etc.

Compared to MM610x-based solutions, what kind of practical range and throughput improvements can we expect with your platform in similar environments?

On the top end the MM8108 offers ~11.5mbps increased bitrate, but that’s only available at the upper end of link quality. The MM8108 has an on chip PA capable of ~26dbm transmit power, which is good for range, but taking advantage of it really depends on your end design’s ability to keep your SNR as high as possible.

With your current test’s performance, until you isolate what’s causing your connectivity issue (eg high noise floor from the environment or localized noise from an interferer, poor signal strength from something like a skewed radial antenna or excessive reflections from poorly matched impedances), switching devices will likely yield similar results. Unless it is something like impedances which would change when switching modules.

Are there any specific antenna recommendations or RF design guidelines that we should follow to achieve reliable range in parking environments?

Antennas are a complex field, definitely something designed for your target regions HaLow frequencies. Avoid electrically small (chip/pcb antennas come to mind) if possible since designing and tuning for those properly takes specialist levels of expertise. MM8108 Hardware Design Guide is a good starting point for RF design.

For deployments involving 10–20 STA devices transmitting JPEG data, do you have any validated performance benchmarks or field test results?

We have throughput data that you can use to gauge your use case with. JPEG data is very nebulous, but it boils down to comparing how many bytes per second you need to send against your link budget.

Regarding RAW/scheduling, is there a recommended approach or configuration strategy to handle burst traffic (image uploads) efficiently?

Nothing that I can think of, this will be more in how your application code is passing data between your STA and AP devices.

You mentioned coexistence considerations between LTE and HaLow — are there any hardware-level recommendations (antenna separation, filtering, shielding) to minimize interference when both radios are active on the same device?

All of what you mentioned, maximize the amount of isolation between the two interfaces.

8

Hi @HarshithG

Currently, we have achieved only a 250-meter range at 915 MHz with a channel bandwidth of 1 MHz.

Just to confirm, you’re doing these tests OTA in Bengaluru? That spectra is cellular licensed in India, your poor range and throughput will be because your devices are competing with cellular traffic. 865-867MHz is the unlicensed spectrum in India that falls within HaLow’s specifications.