Читать книгу Multi-Processor System-on-Chip 2 - Liliana Andrade - Страница 17

The trend in cellular communications over the past generations was to pioneer with a technology in one generation and to optimize it in the next. As mentioned in the abstract, 1G and 2G introduced and optimized voice, 3G and 4G introduced and optimized broadband data streaming and, lastly, 5G and 6G introduce and should optimize the Tactile Internet. Furthermore, the generations also had their killer applications that captured the mass market: for 3G, it was a video call; for 4G, it was social media and streaming; for 5G and 6G, we cannot say for certain, but we can make informed predictions.

As of the advent of 4G, cellular networks are not built for low latency, and the introduction of the low-latency connection between network end points as a key requirement is a challenge for cellular network operators. With the current network infrastructure, it is hard to provide both massive data rates and low latency. Early solutions revolve around trading off one for the other. Hence, in the early adaptation stages, we can expect a killer application that requires low end-to-end latency, but does not require high data rates or vice versa. Likely candidates for low rate - low latency (LRLL) are applications such as factory automation, remote control, trajectory alignment and emergency stop aspects of self-driving for cars, UAVs and robots across a broad field of industries, from construction sites to warehouses. On the other hand, for high rate - high latency (HRHL), a killer application would likely be 8K streaming or other massive data transfers, where latency is not a constraint. Drawn from experience, we can expect 6G to be able to fix and provide both low latency and massive data rates. A likely candidate to be the killer application for high rate - low latency (HRLL) is seamless cellular AR, VR and other Internet gaming-oriented applications. Of course, we can also expect new LRLL and HRHL applications to emerge and further develop in their respective niches. We borrow from the work of (Fettweis et al. 2019) the neatly organized overview and categorization of applications in Figure 1.1.

Figure 1.1. Application mapping on the rate–latency plane with regard to the reliability requirement (Fettweis et al. 2019)

The reliability requirement, as part of the Tactile Internet, affects HW through new procedures and algorithms, which ultimately lead to expanded workloads in terms of additional data throughput and shorter deadlines for processing that data. Potentially, even new operating systems for MPSoCs centered on threat insulation and security will need to be investigated, which is outside the scope of this chapter, but the conclusions are the same. The prospective future 6G applications span vastly different data rates (10 kb/s – 1 Tb/s, i.e. 10⁸ × span) and latency requirements (2 ms – 2 s i.e. 10³ × span).

We have a broad and dynamic workload space with the total number of applications steadily increasing. These applications are sometimes concurrent in their operation, and in, at other times, they are exclusive, which adds another layer of complexity into consideration. For example, a handset user is either watching a video stream or playing an AR-based game while taking a stroll through the city, not both at the same time.

The challenges presented above, combined with new signal processing tasks associated with radio issues when working in new frequency ranges, make HW design choices particularly hard, efficiently balancing between architecture complexity and size, power consumption and cost. The HW challenge is certainly the “half a trillion dollar question”¹. There is no other way to treat this than as an onion problem, and to peel it layer by layer, going step by step, the first step being standard specifications.