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

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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”.

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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.

Quirky: Wink Hub Recall

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April 20, 10:22 a.m. PT: A Wink representative issued the following statement:

“Yesterday, Sunday, April 19, Wink worked diligently to enable a self-service fix for users comfortable making some quick changes to their home’s router settings. Instructions for users recovering their Wink Hub can be found at recovery.wink.com. For those who wish to send their Hub in for repair, they can continue to do so free of charge by visiting hubrepair.quirky.com. We’ll provide a box and shipping label and be sending replacement Hubs as soon as possible.

Approximately 25% of Wink users were impacted by Saturday’s outage and we were able to recover and reconnect 40% of those users within 10 hours. Thousands have already selected the self-service fix and by the end of Monday, April 20 we expect the outage to be limited to 10% of Wink users.”

My take:

This product is absolutely terrible. I purchased it online and should have taken careful attention to the dimensions of this beast. ITS HUGE! There is no place to put this awkward clunky thing. I bought a “smart” light bulb and connected it to hub. I used the mobile app to control the light. The latency is awful! It sometimes takes up to 5 dreadfully long seconds for it to actually turn on. The recall won’t fix the main issue; that main issue being that the product flat out sucks.

Thread – Wireless Communication Protocol

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Thread is also a new wireless protocol that recently has entered the IoT market. Its seven founding members aim to develop Thread, a new IP-based wireless networking protocol, as a better way to connect products in homes and to realize the IoT.

The figure above depicts the Thread protocol stack. Thread has not standardized the application layer, which gives application developers the freedom to develop the applications they deem fit. The IP support of Thread makes it suitable for developing open systems; essentially making it easier to interface with other IP enabled mobile devices. On the network layer (NWK), Thread supports UDP on top of 6LowPAN. Thread also provides a horizontal layer that provides security and authentication functions that enables devices to securely exchange information. On the media access layer (MAC), Thread supports a mesh topology with a maximum of 250 nodes. For the physical layer (PHY) Thread used the IEEE 802.15.4 wireless RF specification that operate in the open 2.4 GHz band, allowing for a data rate of 250 kbps.

IoT connectivity solutions: Media access control layer and network topology

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Media access control layer and network topology

For IoT applications, the main characteristics of the media access layer control (MAC) that need to be considered are multiple access, synchronization, and network topology.

Multiple Access. Looking back at decades of successful cellular system deployment, one can safely conclude that TDMA is a good fit for the IoT. TDMA is suited for low-power operation with a decent number of devices, as it allows for optimal scheduling of inactive periods. Hence, TDMA is selected for multiple access in the MAC layer.

Synchronization. In IoT applications, there are potentially a very large number of power-sensitive devices with moderate throughput requirements. In such a configuration, it is essential to maintain a reasonably consistent time base across the entire network and potentially across different networks. Given that throughput is not the most critical requirement, it is suitable to follow a beacon-enabled approach, with a flexible beacon period to accommodate different types of services.

Network topology. Mobile networks using a cellular topology have efficiently been servicing a large number of devices with a high level of security and reliability, e.g., 5,000+ per base station for LTE in urban areas. This typology is based on a star topology in each cell, while the cells are connected in a hierarchical tree in the network backhaul. This approach is regarded suitable for the IoT and is therefore selected.

The network layer and interface to applications

The network layer (NWK) and the interface to applications are less fundamental as far as power-efficiency and reliability is concerned. In addition, there is more variation in the field of IoT applications. Nevertheless, it is widely acknowledged that IoT applications need to support the Internet Protocol (IP), whether it is IPv4 or IPv6. In addition, the User Datagram Protocol (UDP) and Constrained Application Protocol (CoAP) could provide the relevant trade-off between flexibility and implementation-complexity on resource-constrained devices.

Furthermore, the IoT will represent an immense security challenge, and it is likely that state-of-the-art security features will become necessary. As of today, we can assume 128 bits Advanced Encryption Standard (AES) for encryption and Diffie-Hellman (DH), or the Elliptic Curve Diffie-Hellman (ECDH) variants, can become the baseline for securing communication.