BHCA (Busy Hour Call Attempts) is a teletraffic engineering measurement that indicates the number of calls attempted during the busiest hour of the day in a mobile telephony core network. BHCA is an important parameter for calculations, dimensioning, capacity planning, and design of mobile telephony core networks, as it reflects the peak load and the stress on the network components, such as the MSC (Mobile Switching Center) and the MGW (Media Gateway).
The MSC is a core network node that performs the call control and switching functions for the circuit-switched voice and data services. The MGW is a core network node that performs the user plane functions for the circuit-switched voice and data services, such as transcoding, multiplexing, and interworking. The MSC and the MGW are connected by the Nb interface, which uses the H.248 protocol.
The BHCA affects the MSC and the MGW in the following ways:
• The BHCA determines the processing capacity and the memory requirements of the MSC, as the MSC has to handle the signaling and the call setup for each call attempt. The MSC has to support various protocols and interfaces, such as MAP, ISUP, BSSAP, RANAP, and SIP, to communicate with the other network nodes, such as the HLR, the VLR, the GMSC, the BSC, the RNC, and the MME. The MSC also has to perform various functions and procedures, such as authentication, location update, handover, supplementary services, and charging. The higher the BHCA, the higher the processing capacity and the memory requirements of the MSC.
• The BHCA determines the switching capacity and the bandwidth requirements of the MGW, as the MGW has to handle the user plane data for each call attempt. The MGW has to support various codecs and formats, such as AMR, G.711, G.729, and RTP, to process and transport the voice and data packets. The MGW also has to perform various functions and procedures, such as transcoding, multiplexing, interworking, echo cancellation, and silence suppression. The higher the BHCA, the higher the switching capacity and the bandwidth requirements of the MGW.
Therefore, BHCA is a significiant parameter for calculations, dimensioning, capacity planning and design of mobile telephony core networks, as it affects the performance and the reliability of the MSC and the MGW, which are the main components of the circuit-switched domain.
The difference between BHCA in MSC and BHCA in MGW is that they measure the number of calls attempted at different network nodes and layers. BHCA in MSC measures the number of calls attempted at the Mobile Switching Center, which performs the call control and switching functions for the circuit-switched voice and data services. BHCA in MGW measures the number of calls attempted at the Media Gateway, which performs the user plane functions for the circuit-switched voice and data services, such as transcoding, multiplexing, and interworking. BHCA in MSC and BHCA in MGW are related, but not necessarily equal, as some calls may be dropped or rejected at either node due to various reasons, such as congestion, errors, or failures.