PAwR

PAwR

PAwR (advertising/" class="glossary-term-link" data-term="Periodic Advertising" data-definition="Connectionless data broadcasting at fixed intervals." data-category="GAP & Advertising">Periodic Advertising with Responses) is a Bluetooth 5.4 feature that extends periodic advertising with dedicated response slots, enabling bidirectional communication between a broadcaster and multiple receivers without establishing individual connections. It was designed primarily for electronic shelf label (ESL) systems but has broader applications in connectionless IoT networks.

How PAwR Works

In standard periodic advertising, communication is strictly one-way -- the broadcaster transmits and receivers listen. PAwR adds a structured response phase after each periodic advertising event:

1. Subevent phase: The broadcaster transmits data addressed to specific subgroups of receivers within the periodic advertising event.
2. Response phase: Receivers in the addressed subgroup have assigned time slots to transmit a response back to the broadcaster.

This structure allows a single broadcaster to communicate with thousands of receivers by addressing different subgroups in different subevents. Each periodic advertising event can contain multiple subevents, and each subevent has multiple response slots.

Electronic Shelf Label Use Case

The primary motivation for PAwR is the electronic shelf label (ESL) market, where a single gateway must update thousands of e-ink price tags in a retail store. Before PAwR, ESL systems relied on proprietary protocols or individual BLE connections that did not scale. PAwR provides a standardized solution that scales to over 30,000 labels per gateway.

The bidirectional capability is essential because the gateway needs confirmation that each label received and displayed the correct price. Response slots allow labels to acknowledge updates, report battery status, or signal display errors.

Power Profile

PAwR is extremely power-efficient for receivers. Each label synchronizes to the periodic advertising train and sleeps between its assigned subevents. Since a label might be addressed only once per minute or less, average current consumption can be under 5 uA, enabling multi-year battery life on a coin cell.

Scalability

PAwR supports up to 128 subevents per periodic advertising interval, with each subevent supporting multiple response slots. Combined with the ability to address receivers by subgroup, this architecture scales to tens of thousands of devices per broadcaster -- a capability that was previously only available through proprietary solutions or Bluetooth Mesh.