- This topic has 101 replies, 1 voice, and was last updated 17 years, 5 months ago by
.
-
Posts
-
i am still unable to understand BHCC/BHCA please explaine me..
Does 100 BHCA mean 100 originations and 100 termiantions?
Or does it mean 50 originations and corresponding terminations?
Does the number mean something different for local exchanges than it does for access networks?how I can calculate BHCA AND ERLANG
BHCA = (traffic in Erlang x 3600)/Mean Holding time (in secs)
What is the use of Erlang tables?Kindly send me a copy of the same.
If a line is defined as having 0.09 Erlang traffic capacity,what does it mean?
Hi Wade,
BHCC = Busy Hour Call Coplition
BHCA = Busy Hour Call AttemptesOne is Attemptep ather one is call completed with out droping.
Regards
Mehmet Beyaz
Do not hesitated to contact me if you have further questions
mehmet.beyaz@ttgint.comCan u give me more details about what is ASR. I am not able to get why it is 3, or 40% of network.
Is there any web sites you recommend where i can read more about BHCA, BHCC and Erlang
Hello,
There are a number of questions that have popped up in this thread that I may be able to answer. The first is the difference between a BHCA (Busy Hour Call Attempt) and BHCC (Busy Hour Call Completion) BHCA is the total number of attempts that a device (i.e. a switch, BTS, BSC, etc.) receives in the busy hour. This includes successful calls (the two parties talk to each other) and unsuccessful calls (the two parties are not connected for reasons like line busy, no resources, missed pages, etc.) So BHCA should be bigger than BHCC. You typically worry about BHCA (or BHCC) if you are looking at the capacity of a processor (i.e. the CPU of a switch or BSC) where the devise just processes messages and does not need to dedicate a resource for the duration of a call.
The Erlang is used when you need to provision resources that need to be dedicated for the duration of the call (i.e. trunks, radio channels, etc.) The Erlang is defined (as others on this thread have pointed out) as the calls per hour (or BHCA) * call holding time (in seconds) / 3600 (seconds in an hour.) It is also referred to as the traffic on a link. You would then the Erlang-b formula to determine the number of resources that would be required with only a certain amount of blocking. Some of the standard blocking values are 1% for trunks and 2% for radios in a cell. You would then consult an Erlang-B table to determine the number of channels (links, trunks, etc.) that you would need.
To make sure this is clear, let’s assume that we have a BHCA of 100 and a call holding time of 90 seconds. This would give us 2.5 Erlangs (100*90/3600). If we consult an Erlang-B table or an Erlang-B formula (see this web site for a program or John Belamy’s Digital Telephony book for an Erlang-B table.) and we assume a 1% blocking we would need 8 channels.
One other data point, we can use the Erlang-B table to estimate the traffic a link can support. A T1 (24 channels) can support 15.3 Erlangs with a 1% blocking.
Please email me (creece@awardsolutions.com) if you want to discuss this more.
Thanks
There is a lot of interaction going on here on BHCA and BHCC. While the definitions of both are clear, an examle in the PSTN / I telephony world is missing. I would like to know :
If a softswitch can take 10,000 BHCA and a normal call is held for 90 seconds, then how many simultaneous calls does it mean ?
Pls explain.
Thanks
Dear Muhammad Arshed. (pakistan)
I need ur help regarding my thesis project on Traffic Engineering for voice n data networks”
my email is shaikh20@hyd.paknet.com.pk
please email me.BHCA / hr (3600)
———————–
mean holding time( 90 )= 10000/ (3600/90)= 250
You need to handle 250 simultaneous calls.
Probably this will sound rare, simultaneous calls means they arrive at the same time or be attended at the same time. For a great capacity in a switch means to have power processing plus buffers to queu calls. 1 second is the standard taken to measure capacity for the central processor, some micro seconds are used to attend a call (refer to vendor for your specific case), which means that at the same time just 1 call is attended but within the same second more than one. If your system softswitch handles more processors, means that more than one call could be attended at the same time. Please don get confused processing is different than Traffic, processing has to do with performance or simultaneous events. Thoughs, corrections are welcome
I have a traffic model which says
that the line has to support 2 call originations per minute with average hold time of 165 seconds.So Traffic = 2 x 165 /60 = 5.5 er
But in the field what we see from the logs is that hold time of avg call is very less . It is something as 30 secs. But the calls originations is much more than expected ( around 20 calls /min). Cuz of this failure rate is quite high.
Does it mean that if line has to support the 5.5 er then we can have tradeoff between call originations per mins and call duration.
What I am trying to say , then number of call attempts at busy hours is calculated as following
n = 5.5 er X 60/30 = 11 calls/min
where 5.5er is the traffic to be maintained and,
30sec is the call duration.Does it hold true if there is deviation from number of call attempts per min at the cost of avg. call duration in order to support expected 5.5 er traffic.
Another one.
How do we calculate traffic of packet channels in the networks that service packet calls?WITH ABOVE INFO I WELL UNDERSTOOD THE CONCEPT OF BHCA & BHCC.
NOW I WANT TO KNOW THE RELATION B/W THE BHCC(OR BHCA)AND BLOCKING SWITH.WHETHER REALLY THERE IS A RELATION B/W THEM OR NO RELATION B/W THEM.
PLE HELP ME REGDS THIS.
THANKS
RAMACHANDRA, INDIA
- The forum ‘Telecom Design’ is closed to new topics and replies.
