Bluetooth Related

1) What is Bluetooth and WLAN frequency range?

Bluetooth - ISM (Industrial, Scientific, Medical) band 2.4 MHz + 83 MHz wide
WiFi too same 2.4 MHz + 83 MHz wide

2) Do not they corrupt each other as both working on the same frequency?

Ofcourse. But, each follow different protocols that facilitates to overcome the loss of data due to inteference.

"Bluetooh Hops Away and Tries Again"

 

Bluetooth divides the band into 79 different 1 MHz channels. And, it uses FHSS (Frequency Hop Spread Spectrum) which means Bluetooth hops into these different channels in predefined manner in sync with peer to transmit the data. For example, one bit on 8th channel, next bit on 29th, next bit on 21th, like that. So, if the WiFi channel (explained next) interference causes a loss of data in Bluetooth, as it hops to the next frequency channel, there is chance to get the data.

 

"WiFi slows down and Tries Again"

WiFi on the other hand, divides the band into 22 MHz channels with fixed frequency range (DSSS - Direct Sequence Spread Spectrum) which is fixed for data transmission of one node. There could be maximum of 11 overlapping channels or 3 non-overlapping channels. (So, there can be no more than three different WiFi networks operating in close proximity to one another.) When Bluetooth interferes WLAN channel, WLAN assumes that collision occured due to stations trying to transmit simultaneously and does retransmission of data similar to Ethernet.
 

There are few methods for co-existence. Recently, WLAN is getting moved to 5.2 GHz frequency band.

3) Difference between different Ethernet protocols?

WLAN - CSMA/CA Carrier Sense Multiple Access/Collision Avoidance - Make sure the medium is idle before Transmission. Cannot listen the medium when transmitting, so cannot detect collision. Transmit full frame. If not acknowledged, retransmit.
 

10BASE Ethernet - Half duplex - CSMA/CD Collision Detection - Wait for the medium to be free, transmit single bit and listen the medium if any collision occured. If so, retry after random period. If no, transmit next bit.
 

100Mbps/Full duplex - Separate wires for transmit and reception and direct connection with peer. So, medium itself made collision free.

4) Does low power Bluetooth use the same band?

Yes.　Uses same frequency spectrum range 2.4 GHz ~　2.4835 GHz ISM Band as of classic Bluetooth. But, uses different set of channels, instead of 79 1MHz channels, uses 40 2MHz channels.

Range is 50m (Classic is 100m)
DataRate 1Mbps (Classic is 1~3Mbps)
Peak current consumption ＜15ms (Classic is ＜ 30ms)

Bluetooth smart - 極低電力で動作する無線通信規格Bluetooth Low Energy (BLE)に対応を提示するブランド名
                           きょくていでんりょくでどうさするむせんつうしんきかく Bluetooth Low Engegyにたいおうをていじするブランドな

                        BLEはBluetooth 4.0で採用されている、通信可能距離が短く（50m）、通信速度は低速（1Mbps）、ボタン電池で数年稼動する（アイドルの時数uA、動作する時に＜15mA)
                        BLEはBluetooth 4.0でさいようされている、つうしんかのうきょりはみじかく、つうしんそくどはていそく、ボタンでんちですうねんかどうさせる

                        小型の機器で使われる(時計、リモコン、。。。。)
                        こがたのききでつかわれる

Bluetooth smart ready - is brand name for computers which support BLE as well as Bluetooth classic

(http://e-words.jp/w/Bluetooth20Smart.html)
(http://en.wikipedia.org/wiki/Bluetooth_low_energy)

5) What is the specification for ANT?

ANT - proprietary open access multicast wireless sensor network
Communicates over the same RF spectrum of 2.4GHz (ISM Band)
When working, consumes around 60uA current.

Bluetooth was not designed for large wireless sensor networks. Still, it can form star network of maximum 8 devices (one master and 7 slaves). But, ANT is for large wireless sensor network. ANT supports file transfer of upto 60 kbps.
 

ANT uses adaptive isochronous networking topology. This scheme is very flexible and within a fixed frequency band, data is transmitted in different time slots. Transmission occurs when there is no interference in the frequency band. The radio transmits for less than 150us  per message. The available number of time slots also determined by the messaging period (time interval between data transfer of each node). If the radio band is crowded, ANT allows application to hop to alternative 1MHz channel in the 2.4 GHz band.

6) What are the products supported?

・ARM based System-On-Chip (ARMベースのシステムオンチップ)
・(Single Chip) IC　(シングルチップIC)
・Development Kits (開発キット)
・プロトコルスタック

into four different categories:
1) Bluetooth Low Energy
2) ANT
3) 2.4 GHz RF
4) 1GHz RF

7) Bluetooth support over Linux

BlueZ Linux Bluetooth protocol stack is official Bluetooth stack for Linux.

Directory: linux/net/bluetooth

Configuration option:

Networking support -> Bluetooth subsystem support

 

8) WLAN support over Linux

WLAN has built in support in Linux. Do you remember, WLAN does not have any separate stack as it just uses the same protocol stack with just at hardware level few WLAN drivers and some thin layer to manage the connections comes.

9) PAN setup over Linux

 http://bluez.sourceforge.net/contrib/HOWTO-PAN

 

 it never ends...