Connection-based communication uses the same packet format,with the Message Integrity Check (MIC) field used for encryptedtransmission checks. The adaptive frequency hopping mechanism isapplied to data channels, with the purpose of minimizing channelinterference and maintaining a low loss rate. The GATT further de-fines the rules of exchanging data. The peripheral acts as a GATTserver that stores data in the form of a set of services. Each ser-vice contains a number of characteristics that take the length of asingle PDU. The connected central device, known as GATT client, isable to discover, read, and write to the services and characteristicsaccording to their permissions. As an example, if we have a heartrate monitor acting as a peripheral, its GATT server will contain aHeart Rate Sensor service with a Heart Rate characteristic. This char-acteristic will include the sensor data and the access permissions(e.g., [60bpm, Read Only]).