Which of the following is a low power shorter range wireless technology that is intended to replace wired connectivity for accessories such as speakers or a mouse?

Wireless Communication is the fastest growing and most vibrant technological areas in the communication field. Wireless Communication is a method of transmitting information from one point to another, without using any connection like wires, cables, or any physical medium.

Generally, in a communication system, information is transmitted from transmitter to receiver that is placed over a limited distance. With the help of Wireless Communication, the transmitter and receiver can be placed anywhere between a few meters (like a T.V. Remote Control) to a few thousand kilometres (Satellite Communication).

Short-range wireless communication

Short-range wireless communications systems characterize a wide range of scenarios, technologies, and requirements. We define short-range communications as the systems providing wireless connectivity within a local sphere of interaction.

Short-range wireless communication is of the following types:

• Bluetooth
• Wi-Fi
• ZigBee
• UWB
• IR

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1.Bluetooth

Bluetooth is a wireless communication technology standard used for exchanging data between fixed and mobile devices over short distances. It uses UHF radio waves in the industrial, scientific and medical radio bands, from 2.402 GHz to 2.480 GHz, and building personal area networks (PANs).

The IEEE standardized Bluetooth as IEEE 802.15.1. As of 2009, Bluetooth integrated circuit chips ship approximately 920 million units annually.

>>Operational principle

Originally, Gaussian frequency-shift keying (GFSK) modulation was the only modulation scheme available. Since the introduction of Bluetooth 2.0+EDR, π/4-DQPSK and 8-DPSK modulation may also be used between compatible devices. Devices functioning with GFSK are said to be operating in basic rate (BR) mode where an instantaneous bit rate of 1 Mbit/s is possible. The term Enhanced Data Rate (EDR) describes π/4-DPSK and 8-DPSK schemes, each giving 2 and 3 Mbit/s respectively.

>>Implementation

Bluetooth operates at frequencies between 2.402 and 2.480 GHz, or 2.400 and 2.4835 GHz including guard bands 2 MHz wide at the bottom end and 3.5 MHz wide at the top. This is in the globally unlicensed (but not unregulated) industrial, scientific and medical (ISM) 2.4 GHz short-range radio frequency band. Bluetooth uses a radio technology called frequency-hopping spread spectrum. Bluetooth divides transmitted data into packets, and transmits each packet on one of 79 designated Bluetooth channels. Each channel has a bandwidth of 1 MHz. It usually performs 1600 hops per second, with adaptive frequency-hopping (AFH) enabled. Bluetooth Low Energy uses 2 MHz spacing, which accommodates 40 channels.

2.Wi-Fi (Wireless Fidelity)

Wi-Fi is a family of wireless network protocols, based on the IEEE 802.11 family of standards. These are commonly used for local area networking of devices and Internet access. Devices that can use Wi-Fi technologies include personal computer desktops and laptops, smartphones and tablets, smart TVs, printers, smart speakers, cars, and drones.

Wi-Fi’s wavebands have relatively high absorption and work best for line-of-sight use. Many common obstructions such as walls, pillars, home appliances, etc. may greatly reduce range. However, this also helps minimize interference between different networks in crowded environments. An access point (or hotspot) often has a range of about 20 metres (66 feet) indoors. Hotspot coverage can be as small as a single room with walls that block radio waves. Or it can be as large as many square kilometers using many overlapping access points with roaming permitted between them. Over time the speed and spectral efficiency of Wi-Fi have increased. At close range, some versions of Wi-Fi, running on suitable hardware, can achieve speeds of over 1 Gbit/s.

>>Operational principle

Wi-Fi stations communicate by sending each other data packets: blocks of data individually sent and delivered over radio. Wi-Fi works by the modulating and demodulation of carrier waves. Different versions of Wi-Fi use different techniques, 802.11b uses DSSS on a single carrier, whereas 802.11a, Wi-Fi 4, 5 and 6 use multiple carriers on slightly different frequencies within the channel.

>>Implementation

The 802.11 standard provides several distinct radio frequency ranges for use in Wi-Fi communications: 900 MHz, 2.4 GHz, 5 GHz, 5.9 GHz, and 60 GHz bands. Each range is divided into a multitude of channels. Countries apply their own regulations to the allowable channels, allowed users and maximum power levels within these frequency ranges. The ISM band ranges are also often used.

3.ZigBee

Zigbee is an IEEE 802.15.4-based specification for a suite of high-level communication protocols. It is used to create PANs with small, low-power digital radios, such as for home automation and medical device data collection. Its uses also include small scale projects which need wireless connection. In conclusion, Zigbee is a low-power, low data rate, and close proximity (i.e., personal area) wireless network.

Zigbee is intended to be simpler and less expensive than other wireless PANs (WPANs), such as Bluetooth or  Wi-Fi. Applications include wireless light switches, home energy monitors, traffic management systems, and other equipment that requires short-range low-rate wireless data transfer.

>>Operational principle

This standard specifies operation in the unlicensed 2.4 to 2.4835 GHz (worldwide), 902 to 928 MHz (Americas and Australia), and 868 to 868.6 MHz (Europe) ISM bands. Sixteen channels are allocated in the 2.4 GHz band, spaced 5 MHz apart, though using only 2MHz of bandwidth each. The radios use direct-sequence spread spectrum coding. The digital stream manages this into the modulator. BPSK is used in the 868 and 915 MHz bands, and OQPSK that transmits two bits per symbol is used in the 2.4 GHz band.

>>Implementation

The raw, over-the-air data rate is 250 kbit/s per channel in the 2.4 GHz band, 40 kbit/s per channel in the 915 MHz band, and 20 kbit/s in the 868 MHz band. For indoor applications at 2.4 GHz transmission distance is 10–20 m. This range depends on the construction materials, the number of walls in path and power. The output power of the radios is generally 0–20 dBm (1–100 mW).

4.UWB (Ultra wide band)

Ultra-wideband (also known as UWB) is a radio technology that can use a very low energy level for short-range, high-bandwidth communications over a large portion of the radio spectrum. UWB has traditional applications in non-cooperative radar imaging. Most recent applications target sensor data collection, precision locating, and tracking applications. As of September 2019, UWB support has started to appear in high-end smartphones.

Unlike the spread spectrum, UWB transmits in a manner that does not interfere with conventional narrowband and carrier wave transmission in the same frequency band.

>>Implementation

Ultra-wideband ,formerly known as pulse radio, but the FCC and the International Telecommunication Union Radiocommunication Sector (ITU-R) currently define UWB as an antenna transmission for which emitted signal bandwidth exceeds the lesser of 500 MHz or 20% of the arithmetic center frequency. Thus, pulse-based systems—where each transmitted pulse occupies the UWB bandwidth (or an aggregate of at least 500 MHz of the narrow-band carrier; for example, orthogonal frequency-division multiplexing (OFDM))—can access the UWB spectrum under the rules. Pulse repetition rates may be either low or very high. Pulse-based UWB radars and imaging systems tend to use low repetition rates (typically in the range of 1 to 100 megapulses per second).

5.IR (Infrared)

IR data transmission is also employed in short-range communication among computer peripherals and personal digital assistants. These devices usually conform to standards published by IrDA, the Infrared Data Association. Remote controls and IrDA devices use infrared light-emitting diodes (LEDs) to emit infrared radiation that is focused by a plastic lens into a narrow beam.

The beam is modulated, i.e. switched on and off, to prevent interference from other sources of infrared (like sunlight or artificial lighting). The receiver uses a silicon photo-diode to convert the infrared radiation to an electric current. It responds only to the rapidly pulsing signal created by the transmitter, and filters out slowly changing infrared radiation from ambient light. Infrared communications are useful for indoor use in areas of high population density. IR does not penetrate walls and so does not interfere with other devices in adjoining rooms. Infrared is the most common way for remote controls to command appliances. Infrared remote control protocols like RC-5, SIRC, find use to communicate with infrared.

Comparison

Bluetooth vs Wi-Fi

Bluetooth and Wi-Fi have some similar applications: setting up networks, printing, or transferring files. Wi-Fi is intended as a replacement for high-speed cabling for general local area network access in work areas or home. This category of applications is sometimes called wireless local area networks (WLAN). Bluetooth is intended for portable equipment and its applications. Bluetooth is a replacement for cabling in a variety of personally carried applications in any setting, and also works for fixed location applications such as smart energy functionality in the home (thermostats, etc.).

>Wi-Fi and Bluetooth are to some extent complementary in their applications and usage. Wi-Fi is usually access point-centered, with an asymmetrical client-server connection with all traffic routed through the access point, while Bluetooth is usually symmetrical, between two Bluetooth devices.

>Bluetooth serves well in simple applications where two devices need to connect with a minimal configuration like a button press, as in headsets and remote controls. Wi-Fi suits are better in applications where some degree of client configuration is possible and high speeds are essential, especially for network access through an access node.

Wi-Fi vs ZigBee

WiFi and ZigBee both have their positive qualities, but they obviously come with negatives. What you gain in bandwidth with WiFi is lost in battery power and range, and what you gain with ZigBee’s battery life you lose in range and bandwidth with ZigBee. So like any decision based around link budgets, tradeoffs are crucial to understand.

When speaking specifically about power consumption, ZigBee-based networks generally consume 25% of the power of WiFi networks. ZigBee’s battery life is a major plus over WiFi and needs to be strongly considered if your endpoints will run on batteries.

Bluetooth vs ZigBee vs Wi-Fi

It depends.

What are your particular IoT needs? How big is your house? How far away are your devices? What kind of speed and reliability do you require? What is your budget?

For the home, what Wi-Fi gives you in bandwidth you lose in battery power and range, and what you gain in range and battery life with Zigbee you lose in bandwidth. So, if your devices and endpoints are running on batteries, Zigbee is probably the better choice. On the other hand, if you have a larger IoT-based system or network that you are using for beyond-the-home infrastructures, then you should definitely consider Bluetooth mesh.

Bluetooth vs UWB vs Wi-Fi

>The accuracy advantages of UWB are clear: UWB can measure distance and location to an accuracy of 5 to 10 cm, while Wi-Fi, Bluetooth, and other narrowband radio systems can only reach an accuracy of several meters.

>Modern-day UWB systems provide a data rate of 6 to 8 MB/s, which falls between Wi-Fi and Bluetooth. Previous-generation UWB delivered much higher data rates, up to 100 MB/s, but power requirements and distance range made it impractical for use in mobile devices.

>Though today’s UWB may not be sufficient for streaming HD video, it’s enough for sensor data, security camera streams, instructions, and the like.

>UWB consumes significantly less power than Wi-Fi, although Bluetooth 4.0 also uses extremely low power.

Obviously, one tradeoff against UWB is that Wi-Fi- and Bluetooth-enabled devices are better able to interact with today’s smartphones and tablets. Nonetheless, some companies are implementing UWB, building devices that use both UWB and either Wi-Fi or Bluetooth to get the best of both worlds.

Bluetooth vs IR

>Infrared wireless uses pulses of infrared light to transmit data from one device to another. These pulses are invisible to the naked eye, but can be detected by a sensor in the receiving device. Bluetooth wireless uses radio waves on a particular frequency (2.4 GHz) for data transmission from device to device.

>The effective range for infrared wireless is very short—generally no more than five meters, and often closer to one meter. Bluetooth has a maximum range of 10 meters, which, although twice that of infrared.

>Infrared wireless transmits data in a range between 115 kilobits per second and 16 megabits per second (Mbps), depending on the device. Bluetooth transmits data at a rate between 1 and 3 megabits per second.

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