Next-generation wireless networks: From Gigabit WiFi to White Space

Wireless technology is a unique technology. Although the history of wireless technology has exceeded one hundred years, its development has never stopped. All past, present, and future improvements come from the most fundamental process: better engineering design can make more effective use of space and time.

Various new wireless technologies emerge one after another: 802.11ac promises the transmission speed of a single access point to 1G/second; LTE-A also strives to develop a path for full mobile broadband with local device-device direct communication; the reuse of smart spectrum reduces the bandwidth pressure. In addition, the megabits system combines the original concept of innovative reuse to bring better services.

Wireless technology History

The first wireless signal applied to practice is the moss password, which is vulnerable to interference from other signals in the coverage area.

Tuning technology allows multiple signals to share the spectrum. A better antenna means that the same frequency can be reused without interference; the adjustment of amplitude and frequency means that each signal carries more information.

The biggest breakthrough in wireless technology is the victory of the transistor. Since 1950s, Moore's law has always given engineers the ability to do the most work at the minimum cost. This is especially true for wireless technology. All modern technologies, such as 802.11ac, LTE, and 60 GHz, combine multiple channels across frequencies and spatial paths. processing multiple channels at the same time is an ideal task for the current parallel gibit transistor chip architecture.

This is also applicable to Software-Defined Radio, which relies on a fast processor to repeat the signal processing originally completed by a dedicated circuit in mathematics. This means that a single SDR can manage multiple standards with only a change in programming, which can lead to speculation that one chip or three types of wireless technologies-PAN, LAN, and WAN. However, it is not economical.

Future LAN

The Next Generation Wireless LAN technology 802.11ac will be approved in 2014. It is based on its previous 802.11n concept. 802.11n introduces MIMO to the market. By running multiple converters and receivers on the same channel, MIMO creates parallel channels using the slight time difference between each converter/receiver.

The 60 GHz 801.11ad has a large transmission capacity, but its range is still limited and it cannot penetrate the wall or windows. It is likely to appear in a 3-band device that supports the 2.4GHz and 5GHz standard.

The 802.11n Standard specifies four parallel spatial channels with a maximum channel value of 40 MHz. 802.11ac increases the value to a minimum of 80 MHz and an optional 160 MHz. It also uses a more effective way to write data to the transmission channel: however, it is very close to the theoretical maximum-Shannon Limit-future improvements may come from a wider channel.

60 GHz is the third mainstream band that can be used in wifi technology after 802.11b 2.4GHz and 802.11a/n/ac 5 GHz. Although the accurate frequency distribution varies by country, the recommended standard has four channels, each with a bandwidth of GHz. In MIMO, spatial channels are created by beam or AAS-Adaptive Antenna Steering. The 60 GHz antenna is very small, about 2mm long. Therefore, it is easy to create and configure intensive arrays so that dynamic and compact beam can be created to track mobile devices. The 60 GHz Wi-Fi technology, known as 802.11ad, is promoted by the wireless guitar bit alliance to provide a 7 Gbps transmission speed, but its transmission range is only 10 meters and cannot penetrate walls and windows. The standard will return to 802.11ac or a slower speed.

Use Cases of 60 GHz 802.11ad

Currently, the shortest frequency obtained in this experiment is 240 GHz. in this band, Fraunhofer Research Institute and other German researchers have achieved a speed of 40 Gbps within one kilometer through the Millilink project. They are expected to use multi-channel technology to extend it to the Tb range, so that the technology can replace fiber connections and provide long-distance transmission. However, unlike optical fiber, it is greatly affected during heavy rain days.

Future WAN

People are gradually developing LTE technology because it can provide Mbps speed in nearly 20 different frequencies. Although many operators are doing 4G business, it is not mature: LTE-A like an umbrella covers a variety of intentions to provide the fourth generation of mobile broadband.

Similar ideas include parallel concepts used in 802.11ac, massive MIMO, adjustable upper and lower bandwidths, automatic configuration, bandwidth management, and advanced coding. A single full spectrum base station can provide 10 Gbps transmission speed, but also be divided into different parts; the LTE-A absorbs all the essence of the end-to-end WiMAX standard that has failed the first generation.

The first LTE-A network is being deployed, but it is not full spectrum.

Small Honeycomb

If a user consumes a large amount of bandwidth, the cellular wireless devices with fewer high-capacity masts cannot be expanded with the user's high density.

Small cells (the repeater responsible for 5-users) are expected to solve this problem. The smallest variation is the family base station (Femtocell), which is currently used in the family. While Picocell is used in the office, and mini cells are used in campus. Backhaul-the connection from the cellular network to the telephone system-carries the original Internet connection of the building.

The main problem with deploying enough small cells is to provide the same extra bandwidth to political and commercial cases as the technical case. Frequency distribution can be achieved through band occupancy sensing, central database coordination, and direct coordination between cells in the SON architecture without interference with other cells. However, unlike the registered mobile phone whitelist, once a small cell is made available to the public, paying for the return bandwidth becomes a problem.

LTE-D

LTE-D is between PAN and WAN. It uses LTE-compatible protocols and frequencies, but is used for device-to-device communication. Each device will establish a constantly updated device ing, and can establish a call through the local LTE base station, so you no longer need the phone or the unknown address of the user end.

LTE-D simulation diagram of Shopping Mall: marked as blue users with test objects and nearby small shops can communicate directly with devices, small shops can send advertising information to target customers.

White Space

White Space is a recent innovation in wireless WAN, although it also shows a convergence evolution to more traditional systems.

For all existing frequencies of Overlaying, White Space can use smart networks to perceive, analyze, configure, and use channels that are currently unavailable for services. This can bring efficient and long-distance transmission bandwidth. The areas most likely to be applied are rural broadband and low-speed and high-density IOT, because in this network, distance and sensors send hundreds of bits to the central controller on average per second, it also receives commands that are equally slow.

White Space is widely used in developing countries because the number of allocated frequencies in developing countries is much lower, and the rural population in its existing architecture is also very large. Google SkyNet is a very striking concept that advocates the use of Wired anti-interference hood and White Space systems in large areas to provide affordable wireless networks. The flight broadcast converter can be traced back to the 1920s s, and its current technological innovation is to combine low energy consumption, high bandwidth and long-time lighting on a long-term unmanned light platform.

In the longer term

From self-driving cars to front-line drones, automated transportation will require a wireless architecture and more reliability and connection assurance. The research focuses on Reusing existing architectures in a new way: for example, a mobile phone network can be used as a component of a radar system; a short and fast data packet-intensive end-to-end network can provide a second-level Connection Matrix, this matrix has strong anti-interference ability. It can increase the global bandwidth to a new height, making it possible for self-driving aircraft.

The pace of wireless technology changing the world has not stopped.