For a data to be sent and received in an orderly and organized fashion there are rules and methods that must be followed. These make up communication protocols that govern how data is transmitted over a communication network, and the method by which it is exchanged between the sender and receiver. The lack of such protocols can result in a confusing and incomprehensible communication.
Communication protocols play a vital role in various aspects of data transmission.
Data formatting defines the group of bits that a packet contains, including the address data control and other information
Data routing refers to a process where the most efficient path between source and destination is determined and used
Data sequencing is done to detect duplicates packets or loss of packets
Data security prevents unauthorized users access to confidential data
Flow control regulates the flow of data on communication lines to prevent traffic congestion and ensure appropriate resource sharing and protection
Precedence and order of transmission ensure that all nodes have equal chances to use a communication channel
Error control detects errors contained in messages and then retransmits the erroneous message block for corrections
In addition, communication protocols are responsible for establishing and terminating a connection.
Base Station Management Application Part (BSMAP)
This protocol supports facility management and all radio resource management between the mobile switching centre (MSC) and the base station (BS). BSMAP messages are used to perform functions at the BS or MSC, and used with a Direct Transfer Application Part (DTAP) message to establish a connection for a mobile station.
Base Station System LCS Assistance Protocol (BSSLAP)
BSSLAP defines the layer 3 protocol between the serving mobile location centre (SMLC) and the base station system (BSS), where location services related messages are exchanged. The VMSC acts as a relay in this case.
Base Station System Application Part (BSSAP)
This is defined as the one-user function of the signalling connection control part (SCCP). During point-to-point calls, one SCCP is used per active mobile station by the BSSAP. When it comes to a broadcast or voice group, there is only one connection per cell used and one additional connection for BSS.
Bass Station System Application Part LCS Extension (BSSAP-LE)
This is an extension to the BSSAP protocol that contains parameters in messages that are LCS-specific. It has two subsets — base station system mobile application part-LCS extension (BSSMSP-LE) and direct transfer application part-LCS extension (DTAP-LE).
BSS Management Application Part (BSSMAP)
This protocol supports all the procedures between the BSS and MSC, which require processing and interpretation of information related to single calls and resource management. This is applicable to the GSM technology.
This protocol allows messages to be sent between the base station controller (BSC) and the base transceiver station (BTS). Every message must consist of mandatory and optional information elements.
Call Control (CC)
This is a protocol in telecommunications network that monitors and maintains connections the moment they are established. CC must be supported by every mobile station, or respond to a RELEASE COMPLETE message.
Data Link Connection Identifier (DLCI)
Applicable only to DTAP, this protocol indicates the kind of origination data link connection of the MSC to BSS messages. In a frame-relay transmission system, DLCI defines the destination address of a packet.
This protocol allows a direct exchange of information between the MSC and MS. It comes in two formats — Code Division Multiple Access (CDMA) and Global System for Mobile (GSM).
CDMA is where data is sent over multiple frequencies at the same time, making the most of bandwidth available. In a CDMA system, data is broken down into packets, with each one assigned with a unique identifier.
Other cellular data communication protocols include Mobility Management (MM), Multimedia Messaging Service (MMS), and Radio Resource (RR).