# IEEE 802.11 ah: A Technology to Face the IoT Challenge
## 5 Application and Infrastructure Costs  
In order to provide a more complete view of the viability of an IEEE 802.11 ah-based IoT infrastructure, in this section we give an approximation of its costs. We assume a highly dense scenario of 1 km\({}^{2}\) populated by 10,000 IoT devices, i.e., sensors/actuators connected together in the same area. We calculate the total infrastructural cost to cover 6 and 12 years of operation (short and medium term-operation). We focus this analysis on the costs of the radio interfaces, disregarding the costs of the site (placement and installation of the APs) and the cost of the device, which will be comparable regardless of the wireless technology chosen. A typical scenario based on legacy IEEE 802.11 technology, would require, at least, 50 APs: first, we assume enterprise-level APs supporting up to 200 connected devices per AP and an effective coverage radius of 80 m to serve the whole 1 km\({}^{2}\) area. Second, we consider 20 USD per radio interface and 500 USD per AP. The investment on the aforementioned assets falls under the denominated CAPital EXpenditure (CAPEX, the investment needed to acquire the elements conforming the infrastructure on a project). The OPeration Expenditure (OPEX, the investment that will be needed to maintain the installations in working conditions) can be estimated as the 10% of the CAPEX plus the salaries of the IT staff who will operate and manage the network. Noting that the OPEX is calculated per year, the project generates a total outlay of 740,000 USD in a six year project and an investment of 1,200,000 USD in a twelve year project. On the other hand, we analyze the same scenario based on IEEE 802.11 ah technology with the caveat that there are still no IEEE 802.11 ah products available in the market and, therefore, precise price ranges cannot be given. We assume the same requirements presented previously. In terms of coverage, just two IEEE 802.11 ah APs would be enough. However, in order to guarantee a good service to 10,000 IoT devices, four APs are recommended, each of which can cover a radius of less than 300 m (IEEE 802.11 ah APs can reach more than 1 km in typical outdoor deployments) and can serve 2500 devices (the maximum number of devices allowed in a IEEE 802.11 ah AP is \(\sim\)8000). As explained, the sensor/actuator hardware will cost the same amount as in the previous case. However, IEEE 802.11 ah NICs are expected to be cheaper since they are intended to be integrated in low-cost small devices (assume 15 USD per radio interface); on the other hand, APs are more expensive (assume 1,000 USD per AP). With the same criteria to assess the OPEX, the total cost for a 6 year project with IEEE 802.11 ah would be of 540,000 USD and of 940,000 USD in a twelve year project (close to 25% cheaper). In the same scenario, we estimate deployment costs of other IoT communication alternatives, such as the proprietary solutions LoRaWAN or SigFox. In this case, a sensor radio costs around 10 USD. Three base stations are going to be needed to support 10,000 devices, with an approximately price of 6000 USD each one. Thus, following the same rules for OPEX computation, the total cost would be around 484,000 USD for a six year project and around 850,000 USD for a twelve year project. Those alternatives offer lowest implementation costs in comparison to IEEE 802.11 ah technology, but the higher complexity of LoRaWAN/SigFox interconnection and the limited available bandwidth are the limitations holding back a wider adoption in these IoT technologies. In addition, with regard to the IoT scenario based on cellular technologies, each sensor radio that is going to be connected to the operator infrastructure has an approximate cost of 50 USD. In this case, for the OPEX computation, the 20% of the CAPEX is usually considered, due to the addition of data plane maintenance costs. Thus, the estimated OPEX would be around 1,100,000 USD for a 6 year project and around 2,300,000 USD for a 12 year project, thus making cellular technology the most expensive approach.