The 3 Major Flaws of LoRaWAN

LoRaWAN has three undeniable flaws

  1. Nearly all uplink messages are unacknowledged (you won’t know if the message was ever successfully delivered)
  2. All gateways in range see all uplink traffic (not safe)
  3. LoRaWAN requires an enormous amount of bandwidth (tough to scale, culprit for ISM band traffic, subject to interference from other LoRaWAN gateways)

 

1. Nearly all uplink messages are unacknowledged

LoRaWAN has 1% Duty Cycle Limit for both end devices and the gateway (A duty cycle is the fraction of one period in which a signal or system is active. A period is the time it takes for a signal to complete an on-and-off cycle) In order to support the 1% duty cycle limitation for the gateway, all uplink messages are unacknowledged and uncoordinated, LoRaWAN is considered a “pure-aloha” scheme.

What is pure-aloha: “The idea is applicable to systems in which uncoordinated users are competing for a single channel (shared resource). ALOHA permits users to transmit any time they feel like. Collisions will occur and therefore colliding frames will be destroyed. However, if feedback is available on the destruction, then users will be made aware of their frames have not been transmitted (received) successfully  (1)

“Such a network has about 18% efficiency. This means that 82% of packets are lost when a LoRaWAN network is fully utilized. Since most messages are unacknowledged, the end node does not know its message was missed”(2). The Things Network also confirms this statement by stating “the capacity for downlink messages is even lower than for uplink messages, so don’t waste it.”

2. All gateways in range see all uplink traffic (not safe)

No explanation required.

3. LoRaWAN requires an enormous amount of bandwidth

see my previous post: LORA vs. Sigfox vs. Weightless-P

Sources:

1: Notes on the efficiency of ALOHA: http://www.csee.umbc.edu/~chettri/cs481/notes/NotesOnTheEfficiencyOfALOHA.pdf

2.Link Labs Blog: https://www.link-labs.com/use-cases-and-considerations-for-lorawan/

3. https://iotee.wordpress.com/2015/12/08/lpwan-technology-comparison/

 

LoRaWAN vs. Sigfox vs. Weightless-P: Simulation Results in the “Real World”

In wireless communication, the Hata Model for urban areas, also known as the Okumura–Hata model for being a developed version of the Okumura model, is the most widely used radio frequency propagation model for predicting the behaviour of cellular transmissions in built up areas. This model incorporates the graphical information from Okumura model and develops it further to realize the effects of diffraction, reflection and scattering caused by city structures. This model also has two more varieties for transmission in suburban areas and open areas. (source: Wikipedia)

The Hata Model simulation was conducted for Sigfox, LORA, and Weightless-P with the base station height set at 30m and the end devices heights set at 0.5m. The following simulation was conducted at Ubiik (hardware developers for Weightless-P) but we have checked their math and our team has confirmed the numbers are accurate and unbiased.

Let’s first take a look at the U.S Results (902-928MHz)US compaire.png

 

US2 9.54.52 AM.pngUS3.pngUS 1.png

Now let’s take a look at the results in Europe (863-870MHz). The only difference is LORA is only able to use a smaller bandwidth.

EUR compaire.pngEUR1.pngEUR 2.pngEUR 3.png

 

Let’s see what these numbers mean for an actual Smart Metering deployment (click here)

(If you would like to contribute/make edits/suggestions please contact us at techgu.rooh@gmail.com)

sources: (http://www.ubiik.com/lpwan-comparisons)

POLL: NB-IOT vs unlicensed LPWAN – What do you think?

POLL: NB-IOT vs unlicensed LPWAN – Which technology do you think will be the long-term winner?

NB-IOT vs unlicensed LPWAN

One of 3GPP’s chief low-power, wide-area (LPWA) technologies under development is NB-IOT (narrowband IOT) . Many have been speculating over the differences between NB-IOT and the current LPWAN technologies in the unlicensed frequencies such as LORA, Weightless-P, Sigfox, RPMA. Some individuals have even gone as far as saying NB-IOT will be the death of LPWAN technologies. But that is likely not going to be the case as there will always be a huge difference in use-cases of licensed and unlicensed technologies. The best analogy is WiFi (unlicensed) vs 4G (licensed). The business models and use-cases built around WiFI and 4G are “night and day” .

NB-IOT may not be as robust as we are expecting it be. Check out the following features that are likely to be a slight let-down to NB-IoT enthusiasts

1.No full acknowledgement: By design (found in 3GPP Specification TR45.820) NB-IOT is planned to only acknowledge 50% of messages serviced by the wireless technology. This is due to limited downlink capacity. Unlicensed technologies like Weightless-P allows 100% full acknowledgement of every message. If every message is of high value, you will need to know if your messages are successfully sent/received via an acknowledgement.

 

2. Long Latency: Transmit packet aggregation from buffering of messages and data. NB IOT will not be able to support “real time” responses therefore not suitable for time sensitive applications.

3. IoT devices in the network will not be the priority. The licensed spectrum is EXPENSIVE. Ingenu mentioned “$4.6 billion in a recent auction for only 20 MHz of spectrum!” IoT traffic will always come second to high profit margin, cellular traffic.

4. Long battery Life? The actual battery life will remain unknown until the Cellular LPWA networks are commercially available.

5. Availability: NB IOT is a technology that will be ready a few years down the line.

6. Compatibility: NB-IOT will differ across regions and carriers. Huawei initially pushed for a clean slate NB-IOT technology that would not be backwards compatible with 4G etc. This actually makes a lot of sense as it would be eliminating a lot of the unnecessary overhead.  But just as Huawei began making progress, Nokia and Ericsson began insisting on building upon the frameworks of LTE which means significantly more complexity and unnecessary overhead. Not a very nice foundation for such a huge project.

 

LPWAN Technology Comparison

48ef77882a4360a00d39b680d1c1e9b5ffffb3f3_1_690x387.png

Source: http://www.eejournal.com/archives/articles/20150907-lpwa/

Some buzz/updates from the IoT space:

LoRa :

Range in Urban Environment:  actual tests conclude 1.1 to 2.9 miles.

Making quite a lot of noise and has gained the attention of many early developers. Current pilots and trials have been rather disappointing as far as range and spectrum friendliness. The 3-8km range in urban area is “not as advertised” unless using a really low data rate: much lower than 50kbps. When LoRa is deployed, it indeed renders all other technologies in the ISM bands useless. This is not something that is going to go over well with any of the LPWAN ISM band technologies or RFID technologies wanting to cooperate in the same spectrum.

Sigfox:

Range in urban environment: actual tests conclude 0.6 to 2.9 mile range

Is clearly NOT a technology company. They are operators with a vertically integrated technology. Sigfox proposes an end-to-end solution, from the device to the management interface. It’s up to the user to encrypt data within the 12bytes payload.

Their lacking technology  has caused the Sigfox team to pivot their marketing scheme around being just operators. They want to collaborate with giant telecommunication companies and deploy a $/message business model. In my opinion, the IoT space not ready for a $/message plan. VERY few real IoT application actually make sense to adopt this type of payment plan. With that said, all the technologies that survive in the above comparison chart may potentially be offered by Sigfox in the future . With its current technology, it can only continue to tout its theoretical “coverage”.

sigfox lora.png

 

Weightless-N: A flop . Bi-directional communication has proven to be a must

Weightless-P: Humble figures. The only company marketing “real” coverage of 2km in an dense urban environment. We will see. Look forward to testing out there development kit 2016.

OnRamp (RPMA): Company Ingenu has made an aggressive marketing push of their technology. They stress “simplicity is key:  one worldwide band (2.4 GHz), no sunsetting (we will commit to never sunsetting the RPMA technology), no burdensome certification process.” Unfortunately, 2.4GHz still requires a certification of the end device in Europe, this has a cost. For those who might not know : Sunsetting, in a business context means to intentionally phase something out or terminate it. Why do they stress “no sunsetting”? – I have no clue. It’s not a very strong selling point as all companies can claim to not intend to “intentionally phase out their technology”. Sunsetting is also absolutely beyond Ingenu’s control. Also, Europe has tightened the 2.4GHz regulation this year, some countries may require licenses for OnRamp outdoor usage. Ingenu has no say or influence on these matters. RPMA is 1MHz bandwidth, spread spectrum with large spreading factor. UNB (ultra narrowband) is seemingly the simplest and lowest cost connectivity which covers a few solid cases. BUT if bidirectional communication, more frequent or larger payloads or paging/addressability are needed, then scheduled approaches like the specs of Weightless-P are required .

 

Lora by Semtech : Wireless Connectivity Solution Analysis

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LoRa is a long range wireless connectivity solution developed by Semtech. If you want to learn about the pros of this solution please visit the website: http://www.link-labs.com/lora/

Here are my major concerns regarding this solution.

1)      LoRa is very spectrum unfriendly. When LoRa is transmitting, most systems become inoperable.  LoRa and Sigfox cannot live happily together. LoRa would completely render Sigfox useless if deployed in the same vicinity.

2)      Large bandwidth

3)      High power

4)      No interference awareness or fair-use methods of communication

Check these engineering threads in which TI experts tear LoRa apart.- https://e2e.ti.com/support/wireless_connectivity/f/156/p/343273/1477077.