# IoT-Based Solid Waste Management Solutions: A Survey
## 6 Standard Protocols Used in Waste Management Systems
### Infrastructure Protocols
#### 6.3.4 Physical Layer Protocols  
**Bluetooth Low Energy (BLE). ** Compared to previous versions, Bluetooth Smart uses a short range radio up to 100 meters, ten times longer than the classic Bluetooth and guarantees a 15-fold slower latency [109]. It operates with low power consumption at a transmission power between 0.01 mW and 10 mW, which prolongs the useful life of the device for up to years and makes the BLE a suitable suitor for IoT applications [110], more efficient than the ZigBee not only with regard to the consumption of energy as the rate of power transmitted per bit [111]. The BLE allows a star topology with master devices or writes with a discovery mechanism based on sending messages from the slaves to the master through a dedicated advertising channel that are checked by the master for the discovery to complete. Except when two devices are exchanging data, they are in standby mode. **Electronic Product Code (EPC). ** The EPC is a technology where an individual identification number is stored in an RFID tag used in supply chain management to identify items [112]. The RFID system is divided into two main components, the radio signal transponder (tag) and a tag reader. This tag uses an object's identity storage chip and an antenna to allow communication with the reader utilizing radio waves reflected in the tag so that after, the read information is sent to a specific computer application called object name service (ONS). OEPC is considered a promising technique for the future of IoT applications due to its openness, scalability, interoperability, and reliability [113]. **Global System for Mobile Communications/General Packet Radio Services (GSM/GPRS). ** GSM networks were deployed throughout as an evolution of first-generation mobile communication systems. Initially, they were developed for voice transmission, but later they started to support data transmission through some specific timeslots at a low 9.6 kbit/s rate in the uplink and downlink. After a technical evolution of the GSM, the HSCSD, the data rate had a rise and went to reach 14.4 kbit/s in the uplink and 43.2 kbit/s in the downlink. GPRS was made available to GSM users from GSM version 97 and enabled the use of data services, such as Internet browsing, WAP access, and SMS/MMS, but unlike the previous version, GPRS uses a packet-switched mode and shares the same transmission channel only when the data are to be addressed. The achievable data rates in GPRS depend on the supported multislot class that can reach 21.4 kbit/s with a maximum of 8 downlink or uplink slots [114]. **Wideband Code Division Multiple Access (WCDMA). ** WCDMA was set to provide high speed, packet-switched data services, enabling the more efficient use of the spectrum which provides higher transmission rates of up to 2 Mbit/s. WCDMA supports access to Internet-based services, such as fixed-line services. However, WCDMA has been defined without second generation backward compatibility requirements [115]. **Long Term Evolution-Advanced (LTE-A). ** LTE-A encompasses a set of communication protocols that are well suited to machine type communication (MTC) infrastructures, machine-to-machine communication that does not require human interference, in addition to IoT, especially for smart cities where the long term durability of the infrastructure is expected [116]. LTE-A outperforms other cellular mobile communication solutions related to the cost and scalability of the service and has an architecture that is divided into two parts where the first, called a control network (CN), contemplates mobile devices and treats the IP packets. The other, a radio access network (RAN), deals with wireless communication via radio and establishes the user plan and control protocols. The RAN uses base stations (evolved node) that are connected by an interface, called X2 since the connection of RAN as CN is made through an interface, called S1. Mobile devices or MTCs can connect to base stationseither directly or through the MTCG gateway.