STA2500D datasheet(38/57 Pages) STMICROELECTRONICS

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General specification

STA2500D

38/57

Doc ID 16067 Rev 1

6.13

Bluetooth - WLAN coexistence in collocated scenario

The coexistence interface uses up to 4 WLAN control signal pins, which can be mapped via

software parameter download on different pins of the STA2500D (see Section 7.5).

The functionality of the 4 WLAN control signal pins depends on the selected algorithm, as

explained

below and summarized in Table 25.

Bluetooth and WLAN 802.11 b/g [] [] technologies occupy the same 2.4 GHz ISM band. The

STA2500D implements a set of mechanisms to avoid interference in a collocated scenario.

The STA2500D supports 5 different algorithms in order to provide efficient and flexible

simultaneous functionality between the two technologies in collocated scenarios:

●

Algorithm 1: PTA (Packet Traffic Arbitration) based coexistence algorithm defined in

accordance with the IEEE 802.15.2 recommended practice [].

●

Algorithm 2: the WLAN is the Master and it indicates to the STA2500D when not to

operate in case of simultaneous use of the air interface.

●

Algorithm 3: the STA2500D is the Master and it indicates to the WLAN chip when not

to operate in case of simultaneous use of the air interface.

●

Algorithm 4: Two-wire mechanism

●

Algorithm 5: Alternating Wireless Medium Access (AWMA), defined in accordance

with the WLAN 802.11 b/g [] [] technologies.

The algorithm is selected via an HCI command. The default algorithm is algorithm 1.

6.13.1

Algorithm 1: PTA (packet traffic arbitration)

The algorithm is based on a bus connection between the STA2500D and the WLAN chip:

Figure 13.

PTA diagram

By using this coexistence interface it is possible to dynamically allocate bandwidth to the two

devices when simultaneous operations are required while the full bandwidth can be

allocated to one of them in case the other one does not require activity.

The algorithm involves

●

a priority mechanism, which allows preserving the quality of certain types of link.

●

a mechanism to indicate that a periodic communication is ongoing.

A typical application would be to guarantee optimal quality to the Bluetooth voice

communication while an intensive WLAN communication is ongoing.

Several algorithms have been implemented in order to provide a maximum of flexibility and

efficiency for the priority handling. ST specific HCI commands are implemented to select the

algorithm and to tune the priority handling.

STLC2500D

WLAN

RF_REQUEST

STATUS

FREQ

RF_CONFIRM

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