This post will cover various aspects of the Mobile Devices section of the CompTIA A+ Core 1 certification endeavor.
Table of contents
Bluetooth
Bluetooth is a telecommunications industry specification that describes how mobile devices, computers and other devices can easily communicate with each other using a short-range wireless connection. It commonly requires you to view or verify a particular phrase or personal identification number to be assured that you’re really connecting the device you have in front of you. This is a security function that allows you to control exactly what devices are able to communicate to your mobile phone or your tablet.
Bluetooth technology requires that a low-cost transceiver chip be included in each device. The transceiver transmits and receives in a previously unused frequency band of 2.45 Ghz that is available globally with some variation of bandwidth in different countries. In addition to data, up to three voice channels are available. Each device has a unique 48-bit address from the IEEE 802 standard. Bluetooth connections can be point to point or multipoint.
The maximum Bluetooth range is 10 meters. Data can be exchanged at a rate of 1 megabit per second — up to 2 Mbps in the second generation of the technology. A frequency hop scheme allows devices to communicate even in areas with a great deal of electromagnetic interference. Built-in encryption and verification is provided.
Bluetooth Low Energy (LE)
Bluetooth Low Energy is a power-conserving variant of Bluetooth personal area network (PAN) technology, designed for use by Internet-connected machines and appliances.
Like its predecessor, Bluetooth LE uses frequency hopping wireless technology in the 2.4 GHz unlicensed radio band to interconnect nearby devices. Unlike its predecessor, Bluetooth LE maxes out at just 1 Mbps while consuming just 0.01 to 0.5 watts. That’s up to one third of the speed of Bluetooth Classic, at no more than half the power.
Bluetooth LE is attractive to consumer electronics and Internet-connected machine manufacturers because of its low cost, long battery life, and ease of deployment. From thermometers and heart rate monitors to smart watches and proximity sensors, Bluetooth LE facilitates infrequent short-range wireless data communication between devices, powered by nothing more than a dime-sized battery.
USB Connectors
For the majority of our phones and our tablets, we use USB or Universal Serial Bus as the primary wired connection type. USB is designed for high speed communication and it’s often used to connect our mobile device with our computer or with a power source.
USB Type C
Often referred to simply as USB-C, these plugs and receptacles are rectangular with four rounded corners. Only USB 3.1 Type C plugs and receptacles (and thus cables) exist, but adapters for backward compatibility with USB 3.0 and 2.0 connectors are available. This latest USB connector has finally solved the problem of which side goes up. Its symmetrical design allows it to be inserted in the receptacle in either fashion, so you never have to try again (one of the biggest peeves about earlier USB plugs). These are being widely adopted on smartphones and other devices.
USB Type A
Officially called USB Standard-A, these plugs and receptacles are rectangular and are the most commonly seen USB connectors. USB 1.1 Type A, USB 2.0 Type A and USB 3.0 Type A plugs and receptacles are physically compatible.
USB Type B
Officially called USB Standard-B, these plugs and receptacles are square shaped with an extra notch on top, most noticeable on USB 3.0 Type B connectors. USB 1.1 Type B and USB 2.0 Type B plugs are physically compatible with USB 3.0 Type B receptacles but USB 3.0 Type B plugs are not compatible with USB 2.0 Type B or USB 1.1 Type B receptacles.
USB Powered-B
The USB Powered-B connector is also specified in the USB 3.0 standard. This receptacle is physically compatible with USB 1.1 and USB 2.0 Standard-B plugs, and of course, USB 3.0 Standard-B and Powered-B plugs as well.
USB Micro-A
USB 3.0 Micro-A plugs look like two different rectangular plugs fused together, one slightly longer than the other. USB 3.0 Micro-A plugs are only compatible with USB 3.0 Micro-AB receptacles.
USB 2.0 Micro-A
USB 2.0 Micro-A plugs are very small and rectangular, resembling in many ways a shrunken USB Type A plug. USB Micro-A plugs are physically compatible with both USB 2.0 and USB 3.0 Micro-AB receptacles.
USB Micro-B
USB 3.0 Micro-B plugs look almost identical to USB 3.0 Micro-A plugs in that they appear as two individual, but connected, plugs. USB 3.0 Micro-B plugs are compatible with both USB 3.0 Micro-B receptacles and USB 3.0 Micro-AB receptacles.
USB 2.0 Micro-B
USB 2.0 Micro-B plugs are very small and rectangular, but the two corners on one of the long sides are beveled. USB Micro-B plugs are physically compatible with both USB 2.0 Micro-B and Micro-AB receptacles, as well as USB 3.0 Micro-B and Micro-AB receptacles.
USB Mini-A
The USB 2.0 Mini-A plug is rectangular, but one side is more rounded. USB Mini-A plugs are only compatible with USB Mini-AB receptacles. There is no USB 3.0 Mini-A connector.
USB Mini-B
The USB 2.0 Mini-B plug is rectangular with a small indention on either side, almost looking like a stretched out piece of bread when looking at it head-on. USB Mini-B plugs are physically compatible with both USB 2.0 Mini-B and Mini-AB receptacles. There is no USB 3.0 Mini-B connector.
USB Standards
There are three main USB specifications that USB flash drives can connect through: 1.0, 2.0 and 3.0. Each specification publication allows for faster data transfer rates than the previous version.
USB1.1
This was the original version of the USB, Universal Serial Bus and was released in September 1998 after a few problems with the USB 1.0 specification released in January 1996 were resolved.. It provided a Master / Slave interface and a tiered star topology which was capable of supporting up to 127 devices and a maximum of six tiers or hubs. The master or “Host” device was normally a PC with the slaves or “Devices” linked via the cable.
One of the aims of the USB standard was to minimize the complexity within the device by enabling the Host to perform the processing. This meant that devices would be cheap and readily accessible.
The data transfer rates of USB 1.1 are defined as:
- Low speed: 1.5 Mbps
- Full speed: 12 Mbps
The cable length for USB 1.1 is limited to 5 metres, and the power consumption specification allows each device to take up to 500mA, although this is limited to 100mA during start-up.
USB 1.1 does not allow extension cables or the inclusion of pass-through monitors (due to timing and power limitations).
USB 2.0
The USB 2.0 standard is a development of USB 1.1 which was released in April 2000. The main difference when compared to USB 1.1 was the data transfer speed increase up to a “High Speed” rate of 480 Mbps. However it should be noted that even though devices are labelled USB 2.0, they may not be able to meet the full transfer speed.
The data encoding method for this version of USB is Unicode. In addition to the improvements in data capability USB 2 also saw an increase in the power provision to 1.8A. This enabled USB to provide charge for smartphones that were increasingly charging faster and also for more power hungry peripherals such as external drives, etc. When compared to USB 1, this provided a much needed improvement in current capability.
USB 3.0
The USB3 standard was first demonstrated at the Intel Developer Forum in September 2007. The major feature is what is termed the SuperSpeed bus, which provides a fourth transfer mode which gives data transfer rates of 4.8 Gbit/s. Although the USB3 raw throughput is 4 Gbit/s, data transfer rates of 3.2 Gbit/s, i.e.0.4 GByte/s more after protocol overhead are deemed acceptable within the standard. The standard is also backwards compatible with USB 2.0.
The move to USB 3 saw a change in the data encoding from Unicode to 8b/10b encoding.
Often USB ports on computers, etc. may have the USB symbol with ‘SS’ added, i.e. SS USB. SS USB denotes USB 3, i.e. Super Speed USB.
USB 3.1
USB 3.1 is also known as SuperSpeed+. The use of USB 3.1 doubles the speed of data transfer when compared to USB 3.0. It provides raw data transfer of 10 Gbit/s, and it also reducing line encoding overhead to just 3%. It does this by changing the encoding scheme to 128b/132b.
USB 3.1 also increases the charging capability to 20V, 5A, with the capability to reduce it to 5V as appropriate. This enables users to charge much larger devices including laptop computers, etc. All these advances mean that when compared to previous releases, USB 3.1 provides a significant increase in speed and functionality.
USB 3.2
The next USB iteration is USB 3.2. This was released in September 2017. It retains the existing USB 3.1 SuperSpeed and SuperSpeed+ data modes but introduces two new SuperSpeed+ transfer modes over the USB-C connector with data rates of 10 and 20 Gbit/s (1.25 and 2.5 GB/s). The increase in bandwidth is a result of multi-lane operation over existing wires that were intended for flip-flop capabilities of the USB-C connector.
Another key aspect of USB 3.2 was that the USB-IF introduced a new naming scheme for the different variants with the aim of simplifying the marketing, although whether this has brought ore confusion is a matter of debate. The USB-IF recommended branding the three variants as 5, 10, and 20 Gbit/s transfer modes as SuperSpeed USB 5Gbps (often called USB 3.2 Gen 1), SuperSpeed USB 10Gbps (USB 3.2 Gen 2), and SuperSpeed USB 20Gbps (USB 3.2 Gen 2x2), respectively. The USB-IF decided on “2x2” notation for the highest speed version because the new standard doubles the number of data lanes within a USB-C cable to achieve the 20Gbps transfer speed.