Bluetooth (from the words of the English. Blue - blue and tooth - tooth; pronounced / bluːtuːθ / ), bluetooth [1] [2] - production specification of wireless personal area networks ( Wireless personal area network, WPAN ). Bluetooth provides for the exchange of information between devices such as personal computers (desktops, pocket computers , laptops ), mobile phones , Internet tablets , printers , digital cameras , mice , keyboards , joysticks , headphones , headsets, and speakers on a reliable, free, everywhere available radio frequency for short-range communication. Bluetooth allows these devices to communicate when they are within a radius of up to 10 meters from each other (the range depends heavily on obstacles and interference), even in different rooms.
Bluetooth | |
---|---|
Level (by OSI model ) | Physical |
Protocol assignment | Energy efficient wireless communication devices at a distance of 100 m (from version 5.0 to 400 m) |
Specification | IEEE 802.15.1 |
Developer | Bluetooth SIG |
Title
The word Bluetooth is an adaptation in English of the Danish word “Blåtand” (“Bluetooth”). That was how the Viking King Harald I of the Blue-Teeth , who lived in Denmark about a thousand years ago, was nicknamed. This king got the nickname for the dark front tooth. Harald I ruled Denmark and part of Norway in the 10th century and united the opposing Danish tribes into one kingdom. It is understood that Bluetooth does the same with communication protocols, combining them into one universal standard [3] [4] [5] . Although “blå” in modern Scandinavian languages means “blue”, at the time of the Vikings, it could also mean “black”. Thus, historically, it would be correct to translate the Danish Harald Blåtand as Harald Blacktooth rather than Harald Bluetooth .
In the Russian text, Gramot.ru portal calls use of the spelling “Bluetooth” preferable, and “bluetooth” is acceptable. [6]
The Bluetooth logo is a combination of two Nordic (“Scandinavian”) runes : Hagalaze junior futarka ( ᚼ) and Berkan ( ᛒ ), the sound values of which correspond to the initials of Harald I of Sine-Tooth — h and b (dat.Harald Blåtand, Norwegian Harald Blåtann). The logo is similar to the older logo for Beauknit Textiles, a division of Beauknit Corporation. It uses the merging of reflected K and B for “Beauknit”, it is wider and has rounded corners, but in general it is the same.
History of creation and development
The creation of Bluetooth was started by the manufacturer of telecommunications equipment Ericsson in 1994 as a wireless alternative to RS-232 cables. Initially, this technology was adapted to the needs of the FLYWAY system in a functional interface between travelers and the system.
The Bluetooth specification was developed by the Bluetooth Special Interest Group (Bluetooth SIG) [7] [8] , which was founded in 1998 . It includes Ericsson , IBM , Intel , Toshiba and Nokia . Subsequently, the Bluetooth SIG and IEEE reached an agreement, on the basis of which the Bluetooth specification became part of the IEEE 802.15.1 standard (published on June 14, 2002 ).
Class [9] | Maximum power, mW | Maximum power, dBm | Range, m |
---|---|---|---|
one | 100 | 20 | 100 |
2 | 2.5 | four | ten |
3 | one | 0 | less than 10 |
Bluetooth operation principle
The principle of operation is based on the use of radio waves . Bluetooth radio communication is carried out in the ISM-band ( Eng. Industry, Science and Medicine ), which is used in various household appliances and wireless networks (licensing-free range of 2.4-2.4835 GHz ) [10] [11] . Bluetooth uses the frequency hopping spreading method [12] ( Eng. Frequency Hopping Spread Spectrum, FHSS ). The FHSS method is simple to implement, provides resistance to broadband interference, and equipment is inexpensive.
According to the FHSS algorithm, the carrier frequency of the signal jumps 1600 times per second in Bluetooth [8] (a total of 79 working frequencies 1 MHz wide are allocated, and in Japan , France and Spain, the band already has 23 frequency channels). The switching sequence between frequencies for each connection is pseudo-random and is known only to the transmitter and receiver, which are synchronously rebuilt every 625 µs (one time slot) from one carrier frequency to another. Thus, if several receiver-transmitter pairs are working nearby, they do not interfere with each other. This algorithm is also an integral part of the system for protecting the confidentiality of information transmitted: the transition occurs according to a pseudo-random algorithm and is determined separately for each connection. When transmitting digital data and audio (64 kbps in both directions), different coding schemes are used: the audio signal is not repeated (as a rule), and digital data in case of loss of a packet of information will be transmitted again.
The Bluetooth protocol supports not only the point-to-point connection, but also the point-to-multipoint connection [8] .
Specifications
Bluetooth 1.0
Devices versions 1.0 (1998) and 1.0B had poor compatibility between products from different manufacturers. In 1.0 and 1.0B, the device address transfer (BD_ADDR) was mandatory at the connection establishment stage, which made it impossible to implement anonymity of the connection at the protocol level and was the main drawback of this specification.
Bluetooth 1.1
Bluetooth 1.1 fixed many bugs found in 1.0B, added support for unencrypted channels, indication of received signal strength ( RSSI ).
Bluetooth 1.2
Major improvements include the following:
- Quick connect and discovery.
- Adaptive frequency spread spectrum (AFH), which increases the resistance to radio interference.
- Higher, than in 1.1, data transmission rates, practically up to 1 Mbit / s.
- Enhanced Synchronous Connections (eSCO), which improve the quality of voice transmission in the audio stream, allowing the retransmission of corrupted packets, and if necessary, can increase the delay in audio to provide better support for parallel data transfer.
- Support for the three-wire UART interface has been added to the Host Controller Interface (HCI).
- Approved as IEEE Standard 802.15.1-2005 [13] .
- Data flow control and retransmission (Retransmission Modes) modes for L2CAP have been introduced.
Bluetooth 2.0 + EDR
Bluetooth version 2.0 was released on November 10, 2004. It is backward compatible with previous versions 1.x. The main innovation was the support for Enhanced Data Rate (EDR) to speed up data transfer. The nominal EDR rate is about 3 Mbit / s, however, in practice, this allowed us to increase the data transfer rate only to 2.1 Mbit / s. Additional performance is achieved using various radio technologies for data transfer [14] .
The standard (basic) data transfer rate uses GFSK radio signal modulation at a transmission rate of 1 Mbps. EDR uses a combination of GFSK and PSK modulations with two options, π / 4-DQPSK and 8DPSK. They have higher data rates over the air - 2 and 3 Mbit / s, respectively [15] .
The Bluetooth SIG has published the specification as “Bluetooth 2.0 + EDR Technology”, which implies that EDR is an optional feature. In addition to EDR, there are other minor improvements to the 2.0 specification, and products may conform to Bluetooth 2.0 technology without supporting higher data transfer rates. At least one commercial device, the HTC TyTN Pocket PC, uses “Bluetooth 2.0 without EDR” in its technical specifications [16] .
According to the 2.0 + EDR specification, EDR provides the following benefits:
- Increasing the transmission speed by 3 times (2.1 Mbit / s) in some cases.
- Reducing the complexity of multiple simultaneous connections due to the additional bandwidth.
- Reduced energy consumption due to reduced load.
Bluetooth 2.1
2007 The technology of the advanced query of device characteristics has been added (for additional filtering of the list when pairing), the energy-saving technology Sniff Subrating , which allows increasing the device operation time from one battery charge by 3-10 times. In addition, the updated specification greatly simplifies and speeds up the establishment of communication between two devices, allows you to update the encryption key without breaking the connection, and also makes these connections more secure through the use of Near Field Communication technology.
Bluetooth 2.1 + EDR
In August 2008, Bluetooth SIG introduced version 2.1 + EDR. The new edition of Bluetooth reduces energy consumption by 5 times, increases the level of data protection and makes it easier to recognize and connect Bluetooth devices by reducing the number of steps it takes.
Bluetooth 3.0 + HS
The 3.0 + HS [15] was adopted by the Bluetooth SIG on April 21, 2009. It supports a theoretical data transfer rate of up to 24 Mbps. Its main feature is the addition of AMP (Alternate MAC / PHY), addition to 802.11 as a high-speed message. Two technologies were provided for AMP: 802.11 and UWB, but UWB is not in the specification [17] .
Modules with support for the new specification combine two radio systems: the first provides data transmission at 3 Mbps (standard for Bluetooth 2.0) and has low power consumption; the second is compatible with the standard 802.11 and provides the ability to transfer data at speeds up to 24 Mbps (comparable to the speed of Wi-Fi networks ). The choice of radio system for data transmission depends on the size of the file being transferred. Small files are transmitted over a slow channel, and large files over a high-speed one. Bluetooth 3.0 uses the more general 802.11 standard (without the suffix), that is, it is incompatible with Wi-Fi specifications such as 802.11b / g or 802.11n.
Bluetooth 4.0
The Bluetooth SIG approved the Bluetooth 4.0 specification on June 30, 2010. Bluetooth 4.0 includes protocols:
- Classic Bluetooth
- High speed bluetooth
- Bluetooth low power.
High-speed Bluetooth is based on Wi-Fi, and Classic Bluetooth consists of the protocols of previous Bluetooth specifications.
The frequency of the Bluetooth system (power not more than 0.0025 W).
Frequency band: 2,402,000,000 - 2,480,000,000 Hz (2.402 GHz - 2.48 GHz)
The low-power Bluetooth protocol is primarily intended for miniature electronic sensors (used in sports shoes, simulators, miniature sensors placed on the patients body, etc.). Low power consumption is achieved through the use of a special operation algorithm. The transmitter is turned on only at the time of sending data, which provides the ability to work from a single CR2032 type battery for several years [11] . The standard provides a data transfer rate of 1 Mbit / s with a data packet size of 8–27 bytes. In the new version, two Bluetooth devices will be able to establish a connection in less than 5 milliseconds and maintain it at a distance of up to 100 meters. For this, advanced error correction is used, and the required level of security is provided by 128-bit AES encryption.
Temperature, pressure, humidity, movement speed, etc. sensors based on this standard can transmit information to various control devices: mobile phones, PDAs, PCs, etc.
The first chip with Bluetooth 3.0 and Bluetooth 4.0 support was released by ST-Ericsson at the end of 2009. Currently, a large number of mobile devices are being produced that support this standard.
Bluetooth 4.1
At the end of 2013, the Bluetooth Special Interest Group (SIG) introduced the Bluetooth 4.1 specification. One of the improvements implemented in the Bluetooth 4.1 specification concerns Bluetooth collaboration and fourth-generation LTE mobile communications. The standard provides protection against mutual interference by automatically coordinating the transmission of data packets.
Bluetooth 4.2
December 3, 2014 Bluetooth Special Interest Group (SIG) introduced the Bluetooth 4.2 specification . [18] . Major improvements - increased privacy and increased data transfer speeds.
Bluetooth 5.0
On June 16, 2016, the Bluetooth Special Interest Group (SIG) introduced the Bluetooth 5.0 specification. [19] [20] The changes affected mainly the low-consumption mode and the high-speed mode. The range has been increased 4 times, the speed increased 2 times.
Bluetooth 5.1
A new version of Bluetooth 5.1 will be available very soon. According to the developers, it will be different from previous versions of Bluetooth 5.1 in that with it users will be able to determine the location and direction with maximum accuracy [21] .
Bluetooth protocol stack
Bluetooth has a multi-layered architecture consisting of a main protocol, cable replacement protocols, telephony control protocols and borrowed protocols. Mandatory protocols for all Bluetooth stacks are: LMP , L2CAP and SDP. In addition, devices that communicate with Bluetooth typically use the HCI and RFCOMM protocols.
- Lmp
- Link Management Protocol - used to establish and manage a radio connection between two devices. Implemented by Bluetooth controller.
- HCI
- Host / controller interface - defines the connection between the host stack (that is, the computer or mobile device) and the Bluetooth controller.
- L2CAP
- logical Link Control and Adaptation Protocol — Used to multiplex local connections between two devices using different higher-level protocols. Allows you to fragment and rebuild packages.
- SDP
- Service Discovery Protocol - allows you to detect services provided by other devices, and determine their parameters.
- RFCOMM
- Radio Frequency Communications - cable replacement protocol, creates a virtual serial data stream and emulates RS-232 control signals.
- Bnep
- Bluetooth Network Encapsulation Protocol - used to transfer data from other protocol stacks via the L2CAP channel. It is used to transfer IP packets in the Personal Area Networking profile.
- AVCTP
- Audio / Video Control Transport Protocol - used in the Audio / Video Remote Control profile for transmitting commands over the L2CAP channel.
- AVDTP
- Audio / Video Distribution Transport Protocol - used in the Advanced Audio Distribution profile for transmitting stereo sound over the L2CAP channel.
- TCS
- Telephony Control Protocol — Binary — A protocol that defines call control signals for establishing voice and data connections between Bluetooth devices. Used only in the Cordless Telephony profile.
Borrowed protocols include: Point-to-Point Protocol ( PPP ), TCP / IP , UDP , Object Exchange Protocol ( OBEX ), Wireless Application Environment (WAE), Wireless Application Protocol (WAP).
Bluetooth profiles
Profile - a set of features or capabilities available for a specific Bluetooth device. To work together, Bluetooth devices need all of them to support a common profile.
The following profiles are defined and approved by the Bluetooth SIG development team [22] :
- Advanced Audio Distribution Profile ( A2DP ) - designed to transmit a two-channel stereo audio stream, such as music, to a wireless headset or any other device. The profile fully supports the low-compressed Sub_Band_Codec (SBC) codec and optionally supports MPEG-1.2 audio, MPEG-2.4 AAC and ATRAC, and is capable of supporting codecs defined by the manufacturer. [23]
- Audio / Video Remote Control Profile ( AVRCP ) - designed to control the standard functions of TVs, Hi-Fi equipment and other things. That is, it allows you to create devices with remote control functions. Can be used in conjunction with A2DP or VDP profiles.
- Basic Imaging Profile (BIP) - designed to transfer images between devices and includes the ability to resize images and convert to a supported format of the receiving device.
- Basic Printing Profile ( BPP ) - allows you to send text, emails, vCard and other elements to the printer. The profile does not require specific drivers from the printer, which favorably distinguishes it from HCRP.
- Common ISDN Access Profile (CIP) - for accessing devices to ISDN.
- Cordless Telephony Profile (CTP) is a wireless telephony profile.
- Device ID Profile (DIP) - allows you to identify the class of the device, manufacturer, version of the product.
- Dial-up Networking Profile (DUN) - the protocol provides standard access to the Internet or another telephone service via Bluetooth. Based on SPP, includes PPP and AT commands defined in the ETSI 07.07 specification.
- Fax Profile (FAX) - provides an interface between a mobile or landline phone and a PC on which fax software is installed. Supports a set of AT-commands in the style of ITU T.31 and / or ITU T.32. Voice call or data transfer profile is not supported.
- File Transfer Profile ( FTP_profile ) - provides access to the file system of the device. Includes a standard set of FTP commands, allowing you to get a list of directories, change directories, receive, transfer and delete files. OBEX is used as a transport, based on GOEP.
- General Audio / Video Distribution Profile ( GAVDP ) is the base for A2DP and VDP.
- Generic Access Profile ( GAP ) - the base for all other profiles.
- Generic Object Exchange Profile ( GOEP ) - the base for other data transfer profiles, based on OBEX .
- Hard Copy Cable Replacement Profile ( HCRP ) - provides a simple alternative to the cable connection between the device and the printer. The minus profile is that the printer requires specific drivers, which makes the profile non-universal.
- Hands-Free Profile (HFP) - used to connect a wireless headset and phone, transmits mono sound in one channel.
- Human Interface Device Profile ( HID ) — обеспечивает поддержку устройств с HID (Human Interface Device), таких как мыши, джойстики, клавиатуры и проч. Использует медленный канал, работает на пониженной мощности.
- Headset Profile (HSP) — используется для соединения беспроводной гарнитуры (Headset) и телефона. Поддерживает минимальный набор AT-команд спецификации GSM 07.07 для обеспечения возможности совершать звонки, отвечать на звонки, завершать звонок, настраивать громкость. Через профиль Headset, при наличии Bluetooth 1.2 и выше, можно выводить на гарнитуру всё звуковое сопровождение работы телефона. Например, прослушивать на гарнитуре все сигналы подтверждения операций, mp3-музыку из плеера, мелодии звонка, звуковой ряд видеороликов. Гарнитуры, поддерживающие такой профиль, имеют возможность передачи стереозвука, в отличие от моделей, которые поддерживают только профиль Hands-Free.
- Intercom Profile (ICP) — обеспечивает голосовые звонки между Bluetooth-совместимыми устройствами.
- LAN Access Profile (LAP) — обеспечивает доступ Bluetooth-устройствам к вычислительным сетям LAN , WAN или Интернет посредством другого Bluetooth-устройства, которое имеет физическое подключение к этим сетям. Bluetooth-устройство использует PPP поверх RFCOMM для установки соединения. LAP также допускает создание ad-hoc Bluetooth-сетей.
- Object Push Profile (OPP) — базовый профиль для пересылки «объектов», таких как изображения, виртуальные визитные карточки и др. Передачу данных инициирует отправляющее устройство (клиент), а не приёмное (сервер).
- Personal Area Networking Profile (PAN) — позволяет использовать протокол Bluetooth Network Encapsulation в качестве транспорта через Bluetooth-соединение.
- Phone Book Access Profile (PBAP) — позволяет обмениваться записями телефонных книг между устройствами.
- Serial Port Profile ( SPP ) — базируется на спецификации ETSI TS07.10 и использует протокол RFCOMM . Профиль эмулирует последовательный порт, предоставляя возможность замены стандартного RS-232 беспроводным соединением. Является базовым для профилей DUN, FAX, HSP и AVRCP.
- Service Discovery Application Profile (SDAP) — используется для предоставления информации о профилях, которые использует устройство-сервер.
- SIM Access Profile (SAP, SIM) — позволяет получить доступ к SIM-карте телефона, что позволяет использовать одну SIM-карту для нескольких устройств.
- Synchronisation Profile (SYNCH) — позволяет синхронизировать персональные данные (PIM). Профиль заимствован из спецификации инфракрасной связи и адаптирован группой Bluetooth SIG.
- Video Distribution Profile ( VDP ) — позволяет передавать потоковое видео. Поддерживает H.263 , стандарты MPEG-4 Visual Simple Profile, H.263 profiles 3, profile 8 поддерживаются опционально и не содержатся в спецификации.
- Wireless Application Protocol Bearer (WAPB) — протокол для организации P-to-P (Point-to-Point) соединения через Bluetooth.
Security
В июне 2006 года Авишай Вул [24] и Янив Шакед опубликовали статью [25] , содержащую подробное описание атаки на устройства Bluetooth. Материал содержал описание как активной, так и пассивной атаки, позволяющей заполучить PIN-код устройства и в дальнейшем осуществить соединение с данным устройством. Пассивная атака позволяет соответствующе экипированному злоумышленнику «подслушать» (sniffing) процесс инициализации соединения и в дальнейшем использовать полученные в результате прослушки и анализа данные для установления соединения (spoofing). Естественно, для проведения данной атаки злоумышленнику нужно находиться в непосредственной близости и непосредственно в момент установления связи. This is not always possible. Поэтому родилась идея активной атаки. Была обнаружена возможность отправки особого сообщения в определённый момент, позволяющего начать процесс инициализации с устройством злоумышленника. Обе процедуры взлома достаточно сложны и включают несколько этапов, основной из которых — сбор пакетов данных и их анализ. Сами атаки основаны на уязвимостях в механизме аутентификации и создания ключа-шифра между двумя устройствами.
Инициализация bluetooth-соединения
Инициализацией bluetooth-соединения принято называть процесс установки связи. Её можно разделить на три этапа:
- генерация ключа Kinit ,
- генерация ключа связи (он носит название link key и обозначается, как Kab ),
- аутентификация.
Первые два пункта входят в так называемую процедуру паринга.
Паринг (pairing), или сопряжение, — процесс связи двух (или более) устройств с целью создания общего секретного значения Kinit, которое они будут в дальнейшем использовать при общении. В некоторых переводах официальных документов по bluetooth можно также встретить термин «подгонка пары». Перед началом процедуры сопряжения на обеих сторонах необходимо ввести PIN-код.
Kinit формируется по алгоритму E22, который оперирует следующими величинами:
- BD_ADDR — уникальный MAC-адрес BT-устройства длиной 48 бит;
- PIN -код и его длина;
- IN_RAND — случайная 128-битная величина.
Для создания ключа связи Kab устройства обмениваются 128-битными словами LK_RAND(A) и LK_RAND(B) , генерируемыми случайным образом. Далее следует побитовый XOR с ключом инициализации Kinit . И снова обмен полученным значением. Затем следует вычисление ключа по алгоритму E21.
Для этого необходимы величины:
- BD_ADDR
- 128-битный LK_RAND (каждое устройство хранит своё и полученное от другого устройства значения)
На данном этапе pairing заканчивается и начинается последний этап инициализации bluetooth — Mutual authentication, или взаимная аутентификация. Основана она на схеме «запрос-ответ». Одно из устройств становится верификатором, генерирует случайную величину AU_RAND(A) и посылает его соседнему устройству (в открытом виде), называемому предъявителем. Как только предъявитель получает это «слово», начинается вычисление величины SRES по алгоритму E1, и она отправляется верификатору. Соседнее устройство производит аналогичные вычисления и проверяет ответ предъявителя. Если SRES совпали, то устройства меняются ролямии процесс повторяется заново.
E1-алгоритм оперирует такими величинами:
- Случайно созданное AU_RAND
- link key Kab
- Свой собственный BD_ADDR
Атака на сопряжение
Если злоумышленнику удалось прослушать эфир и во время процедуры сопряжения он перехватил и сохранил все сообщения, то далее найти PIN можно используя перебор.
The first to notice this vulnerability was Englishman Ollie Whitehouse in April 2004. He first suggested intercepting messages during pairing and trying to figure out the PIN by brute force using the information obtained. However, the method has one major drawback: an attack can only be carried out if it was possible to overhear all authentication data. In other words, if the attacker was out of the air during the start of the pairing or missed some value, then he is unable to continue the attack.
Rematch Attack
Vulu and Shakedu managed to find a solution to the difficulties associated with the Whitehouse attack. A second type of attack was developed. If the pairing process has already begun and the data is missed, it is impossible to conduct an attack But if the devices have already been contacted, they saved the Kab key and started mutual authentication, you can force the devices to re-initiate the pairing process in order to carry out the above-described pairing attack.
This attack requires sending the right messages at the right time. Standard commercially available devices are not suitable for this purpose.
Using any of these methods, an attacker can initiate a basic mate attack. Thus, having these two attacks in an arsenal, the malefactor can steal a PIN code freely. Further, having a PIN code, he will be able to establish a connection with any of these devices. And it is worth considering that in most devices, security at the level of services available via bluetooth is not ensured at the proper level. Most developers place their stake on the security of pairing. Therefore, the consequences of an attacker's actions can be different: from stealing the phone’s notebook to setting up an outgoing call from the victim’s phone and using it as a listening device.
Estimation of PIN pick time
The Bluetooth protocol actively uses the E22, E21, E1 algorithms based on the SAFER + cipher. Bruce Schneier confirmed that vulnerability is critical. PIN selection in practice works fine and can be made in real time [26] . Below are the results obtained on a Pentium IV HT at 3 GHz:
Length (characters) | Time (sec) |
---|---|
four | 0.063 |
five | 0.75 |
6 | 7,609 |
Specific implementations of the above attacks can work at different speeds. There are many ways to optimize: special compiler settings, various implementations of loops, conditions and arithmetic operations. Avishay Vul and Yaniv Shaked have found a way to significantly reduce the time to search through a PIN.
Increasing the length of the PIN is not a panacea. Only pairing devices in a safe place can partially protect against the attacks described. An example is a bluetooth headset or car handsfree. Initialization of communication (when turned on) with these devices can occur many times during the day, and it is not always possible for the user to be in a protected place.
Application
The radius of operation of BT2 devices does not exceed 16 meters, for BT1 - up to 100 m (class A). These numbers are declared standard for direct visibility, in reality, one should not expect work at a distance of more than 10–20 m. Such long-range action is not enough for effective use of attacks in practice. Therefore, even before the detailed elaboration of the attack algorithms, the BlueSniper antenna rifle developed by John Herington was presented to the public at Defcon-2004. The device connects to a portable device - a laptop / PDA and has sufficient directivity and power (effective work up to 1.5 km).
Coexistence with other protocols
Frequent change of the working channel FHSS in a wide range of frequencies gives a chance for coexistence with other protocols. With the introduction of adaptive AFH, the situation has improved slightly [27] .
Debugging and certification
Debugging and control of compliance with the standard is complicated by active neighbors in the range (for example, Wi-Fi). There are solutions that allow you to decode and monitor all connections simultaneously in all 79 Bluetooth channels.
See also
- IEEE 802.15.4
- Bluetooth stack
- Bluejacking
- Uwb
Notes
- ↑ Bluetooth . “The spelling academic resource ACADEMOS” . bluetooth The appeal date is March 9, 2018.
- ↑ GRAMOTA.RU - reference and information Internet portal "Russian language" | Dictionaries | Word Verification
- ↑ Monson, Heidi Bluetooth Technology and Implications . SysOpt.com (December 14, 1999). The appeal date is February 17, 2009. Archived August 24, 2011.
- ↑ About the Bluetooth SIG (inaccessible link) . Bluetooth SIG. The appeal date is February 1, 2008. Archived on March 18, 2006.
- ↑ Kardach, Jim How Bluetooth its name (May 3, 2008). The appeal date is February 24, 2009. Archived August 24, 2011.
- ↑ Question No. 244488 Unsolved . Diploma.ru - "Valid:" bluetooth. " But it is better to write in Latin. " The appeal date is March 9, 2018.
- ↑ About the Bluetooth SIG (inaccessible link) . Bluetooth SIG . The date of circulation is March 20, 2008. Archived January 10, 2006.
- ↑ 1 2 3 Vishnevsky et al. Broadband wireless data networks. - M .: Technosphere, 2005. - 592 p. - ISBN 5-94836-049-0 .
- ↑ Joshua Wright. Dispelling Common Bluetooth Misconceptions (English) . SANS. The appeal date is August 25, 2018.
- ↑ Soltanian A., Van Dyck Performance Performance of the Bluetooth system in fading dispersive channelsand interference // IEEE Global Telecommunications Conference, 2001 (GLOBECOM '01). - p . 3499-3503 .
- ↑ 1 2 BLUETOOTH SIG Introduces BLUETOOTH Low Energy Wireless Technology, the Next Generation BLUETOOTH Wireless Technology (English) (not available link) . Official site. The appeal date is January 16, 2010. Archived December 20, 2009.
- ↑ Biteleva A. Technology of multimedia access . Tele-Sputnik magazine 8 (82) (August 2002). The appeal date is January 15, 2010. Archived August 24, 2011.
- EE IEEE Std 802.15.1-2005 - IEEE Standard for Information Technology - Specifications for Part 15.1: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Wireless Personal Area Networks (WPANs)
- ↑ Guy Kewney. High speed Bluetooth comes a step closer: enhanced data rate approved . Newswireless.net (November 16, 2004). The appeal date is February 4, 2008. Archived August 24, 2011.
- ↑ 1 2 Specification Documents (Unavailable (not available link) . Bluetooth SIG. The appeal date is February 4, 2008. Archived January 17, 2008.
- ↑ HTC TyTN Specification (PDF). HTC. The date of circulation is February 4, 2008. Archived March 8, 2008.
- ↑ David Meyer. Bluetooth 3.0 released without ultrawideband . zdnet.co.uk (April 22, 2009). The appeal date is April 22, 2009. Archived August 24, 2011.
- ↑ SIG introduces Bluetooth 4.2
- 5.0 Bluetooth 5.0: Here's the New Wireless Standard Matters
- ↑ Bluetooth 5.0 to Quadruple Range, Double Speed | News & Opinion | PCMag.com
- ↑ Cris Hoffman. Bluetooth 5.1: What's New and Why It Matters How to geek (January 31, 2019). The appeal date is February 4, 2019.
- ↑ ComputerPress №3, 2013 , p. 36
- ↑ Error Archived December 6, 2010.
- ↑ Prof. Avishai wool
- ↑ Yaniv Shaked, Avishai Wool. Cracking the Bluetooth PIN (eng.) : Journal. - School of Electrical Engineering Systems, Tel Aviv University, 2005. - 2 May.
- ↑ Ellisys. Bluetooth Security - Truths and Fictions (English) .
- Ex Coexistence issues for a 2.4GHz wireless audio streaming in the presence of bluetooth paging and WLAN .
Literature
- Sergey Asmakov. Bluetooth interface: let's deal with the nuances // ComputerPress : magazine. - 2013. - March 12 ( No. 3 (279) ). - p . 34-36 . - ISSN 0868-6157 .
Links
- Bluetooth tutorial
- Specifications (English)
- Bluetooth security
- Bluetooth 2.0 / EDR - well completed old
- Yaniv Shaked, Avishai Wool. Cracking the Bluetooth PIN
- NFC Forum