One very important type of wireless network are cellular. Cellular are being used worldwide, and there are billions of users of cellular networks. Let's look at some of the characteristics that make a typical cellular network. The name cellular comes because of the topology, where to reuse the spectrum to make very efficient use of the spectrum, which is a very scarce resource, transmitters, or base stations, are spread around our geography to make sure that each base station is actually using the local resources around it. Cellular networks are a type of wide area network. So it is providing cover [INAUDIBLE] on our nation or on our country. And it provides mobility, so it means that users are able to move between different cells, whether they are walking, or whether they're in a car or on a fast train, or any other type of vehicle. Because cellular networks are using licensed spectrum, they are capable of delivering different types of quality of service and different type of services. They can deliver consumer services, such as basic voice to enhanced mobile broadband, and in some cases, as we will see, also deliver M2M and IoT communications. Because they are public networks used by many, many users, they have very strong security mechanisms to ensure that both the network and the users are protected. The use of SIM cards protects both the network and the user, so the user can trust that the network is talking is not a rogue network. And the network also can trust that the user accessing it is not a rogue user. Looking at the history of cellular networks, we'll start with 2G. It came in the 1990s. There were actually multiple technologies that fell under the 2G umbrella. In different regions of the world, we have different types of technologies being used, such as GSM, CDMA, et cetera. All these networks generally only provided voice service, telephony service. In the 2000s, we saw the operation of 3G. 3G brought data services on top of voice that was given in the previous generation. There were mainly two standards under the 3G umbrella, UMTS and CDMA 2000 used in different regions of the world. With 4G, we saw really mobile broadband. The data services being given by 3G were fairly slow. Latency was high. It wasn't the best user experience. But with 4G all those issues were resolved. And we saw really real mobile broadband being delivered to users. There were two main contenders for the 4G crown, two different technologies. One was WIMAX, the other one was LTE. But LTE became really the global standard. In the next year or so, we will see the first 5G networks come into the market. 5G-NR are specified by 3GBP is the global technology of choice, which is undisputed. 5G is going to bring the different type of services to what we saw before. All the previous generations were mostly centered around delivering consumer services. 5G is going to expand the portfolio of users and the different type of use cases that can be delivered over 5G. It's going to to be focused on M2M, on internet of things, connecting millions of devices, providing ultra reliable communications, providing low latency communications, in addition of also delivering the typical consumer services that we know today. In this table, we can see a comparison between the different type of technologies and the different types of generations. We had GSM for example, whose primary services delivered were voice and some M2M, but the downlink and uplink speeds were fairly limited at 14.4 kilobits per second. GPRS provided some advancements in the data services that could be delivered, but didn't amount to much more than being able to do email. In the third generation, we saw various technologies like UMTS, TD-SCDMA and CDMA2000. That provided voice, video, and some data. The data was good for browsing, but really not good enough for other type of services, like video streaming. Part of the evolution of UMTS was the HSPA, high speed packet access. This enabled more advanced mobile broadband, much higher throughput, but latency was still an issue. This was resolved in 4G. Both WIMAX and LTE technologies were very much focused on delivering data services and mobile broadband, high quality mobile broadband. WIMAX wasn't developed as quickly. LTE became the global standard, but we can see that WIMAX delivered 70 megabytes per second downlink, and up to 70 megabytes per second uplink. LTE in its various generations can deliver, can achieve much higher throughput, up to three gigabytes per second downlink and 1.5 gigabytes per second uplink. LTE eventually in further generations of LTE also delivered voice services on what's commonly known as voice over LTE, and also has been enhanced to deliver some IoT services with the operation of for example, narrowband IoT or category M1 type of services. With 5G-NR, all of this will be delivered almost from the start. Right now, initial focus has been enhanced mobile broadband with much higher speeds and much higher capability than LTE. We can see the peak theoretical downlink speeds are 20 gigabytes per second in the downlink and 10 gigabytes per second in the uplink. But quickly after that first release, we will see the operation of new type of services like ultra reliable, low latency communications, and massive IoT that will enable these broad range of uses of 5G.
