IEEE Future Directions
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Stating that connectivity is a major enabler for a smart city is stating the obvious. As a matter of fact, all cities today, more or less smart, rely on a pervasive communications infrastructure collecting data, sending alert to citizen, supporting a variety of applications that orchestrate the city and deliver services.
Public communications networks is always leveraged but there are also other private networks that are used by cities, like dedicated radio system for police communications. Many cities have deployed, and are expanding, WiFi hot spots to provide citizens with access points to city services and information.
So what would 5G add to these infrastructures and, conversely, how could cities leverage on 5G to provide better connectivity, services, information at … lower cost?
5G has been (or is being) designed to serve a variety of communications needs, even though the press (and often Telecom Operators) focuses on higher speed/capacity and lower latency. In a city environment, higher speed (beyond the one already provided by 4G, in the ten of Mbps range) is not a plus. If you can deliver 10Mbps (even 4Mbps) you are fine. Capacity is sometimes an issue and you can increase capacity by deploying more cells (which is basically true for any Gs!). The problem of course is that deploying more cells cost money and this additional investment makes sense if you are going to use that capacity and users are willing to pay for it. This is seldom the case, given the maturity level reached by the market.
Are 5G cells in an urban environment cheaper than equivalent 4G cells? No, they are not. However, and it is a BIG however, with 5G there is the possibility of clustering different sorts of cells seamlessly integrating them in a seamless infrastructure (meaning that from the point of view of the user there is no perception of the variety of cells involved). As an example you can have a WiFi hot spot, a 4G cell, a bluetooth enabled window-shop, a 28GHz millimetre way link, a vehicle created cell… A user will be able to connect to any of these cells/gateways AND to move from one to the other without losing connectivity. This is because the session management can be shifted from the network (owned by a single party, like an Operator) to the device being used (like a smartphone). Hence the seamless transfer from one cell to the next available one.
This changes the rules of the game since the cost of deployment and operation of these cells no longer gravitate on a single party but it is spread among many. A municipality intending to increase its WiFi coverage to provide better connectivity to its citizens will have to invest quite a bit of money. With 5G it can piggy back on WiFi areas deployed by shop-keepers, by taxis, by buses… From a technical point of view 5G will take care of managing the communications transfer from one cell (in any given technology) to another (in any given technology). This is sometimes referred to as “vertical roaming” as opposed to the “horizontal roaming” of today where the handover takes place among homogenous technology (e.g 4G to 4G, 3G to 4G).
The seamless integration of different networks/gateways/technologies within the terminal opens up another interesting opportunity from the point of view of a city. Municipalities are swapping incandescent lighting for LEDs illumination. LEDs can be modulated and therefore can be used to send signals (the technology name is LiFi, mimicking the WiFi, with Li standing for Light). The problem is that you can use lamp posts to send signals but they cannot receive signals so it is a one way communications. Well with the capability of 5G of managing different “physical channels” for the upstream and downstream communications one could imagine a citizen getting on his smartphone the downstream information via LiFi and interacting with that using an upstream channel like a radio cell… Cute!
This is the first interesting, very interesting advantage of 5G for a city.
The second one is somewhat specular: a municipality that has invested in communications infrastructures can make these infrastructures seamlessly available to third parties (when they have spare capacity) generating revenues. This opens the door to more effective PPP (Public Private Partnership) in the development of infrastructures.
A second feature of 5G that can be of interest to a city is the coexistence of several protocols, including some with very low power budget. These are ideal to serve sensors in a urban environment when there is no availability of mains (or where it would be costly to provide one). The progress in sensors (and in low power electronics) has made possible the creation of sensors that are powered via energy scavenging, like turning the vibration of the road tarmac into power. This is sufficient to operate the sensor but it is not enough to support communications links of a sizeable length. 5G can provide the solution by enabling local communications with these sensors, harvesting data from them through public buses driving along, taxis and even cars that have accepted to serve as relay points.
Finally, 5G can be designed, from an architectural point of view, to operate just at the edges thus slashing down latency below a millisecond, thus enabling car to infrastructure communications supporting self driving cars.
