How much does each timeslot period tier slow down BLE?

RE: How much does each timeslot period tier slow down BLE?

Håkon Alseth — Mon, 15 Aug 2022 07:34:45 GMT

Hi,

[quote user="Cilan"]One more question, why does the timeslot period decrease with higher rate for gazell?[/quote]

Each "gazell period" can do one transaction. One transaction to send, and one to receive an ACK.

This how the gazell protocol is implemented for nRF5-series devices:

https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/gzll_02_user_guide.html?cp=8_1_5_4#timeslot

Please note that gazell timeslots are different from the SoftDevice timeslot API, although they share the same name, which can be a bit confusing.

Kind regards,

Håkon

RE: How much does each timeslot period tier slow down BLE?

Abraham Hamidi — Fri, 12 Aug 2022 18:40:15 GMT

Thank you. One more question, why does the timeslot period decrease with higher rate for gazell? From what I could find in the docs, it said >=60 us for 2Mbps, then I don't remember but something like >=90 us for 1Mbps. Why is higher timeslot period lower gazell rates? Shouldn't it be other way around?

RE: How much does each timeslot period tier slow down BLE?

Håkon Alseth — Fri, 12 Aug 2022 11:51:58 GMT

Hi,

The timeslot you request, and possibly extend, will be handled as per the specification:

https://infocenter.nordicsemi.com/topic/sds_s132/SDS/s1xx/multiprotocol_operation/multiprotocol_support.html?cp=4_7_3_0_8

I would strongly recommend that you read this to understand how the timeslot API works and behaves.

[quote user=""]Using the period required for 2Mbps Gazell, 600us, how much does this slow down BLE (bandwidth/# packets)?[/quote]

The problem is the other way around. Depending on when the BLE link needs to be serviced, your timeslot period will yield.

Please see this chapter: https://infocenter.nordicsemi.com/topic/sds_s132/SDS/s1xx/concurrent_multiprotocol_tsl_api/performance_considerations.html

Kind regards,

Håkon