TMSI re-allocation, load balancing at MSC Pool

[inexia]

Dear Core Expert

I am implementing MSC POOL currently, It's working right now, but I am still confuse with some parametes.

At my manual book mention that: "to implement MSC Pool, TMSI reallocation when location update MUST be set".

My question is:
1. For non pool MSC, what the what should I consider to choose whether TMSI REALOCATION activated or not?

2. NRI is part of TMSI, but why MSC MUST re-allocated new TMSI every time after location update or service access? It should be can use old TMSI, is it?

3. How load Balancing work at MSC Pool? We have 2 MSCs in one POOL here, VLR subscriber at both MSC almost same, I am still confuse how it can be like that. When subscriber perform location update using IMSI, how BSC can choose which MSC will serving this MS?


Thanks For your information

Regards,
Taufan

[s52d]

Hi!

3: load balancing is done in radio. Check BSS/RNC docs for your beloved vendor.
Your BSS/RNC obviously split 50/50 on LAU without proper TMSI.

2. TMSI must be VLR specific. It ***might*** be your vendor has either
TMSI reallocation on LA change, or none.
It is NRI that matters.

1. You need TMSI in order to have NRI.

On top: test load balancing. Emulate emergency to clean up one VLR.
We keep scripts around for normal O&M.
Be ready for suprices ....

BR
s52d



Dear Core Expert

I am implementing MSC POOL currently, It's working right now, but I am still confuse with some parametes.

At my manual book mention that: "to implement MSC Pool, TMSI reallocation when location update MUST be set".

My question is:
1. For non pool MSC, what the what should I consider to choose whether TMSI REALOCATION activated or not?

2. NRI is part of TMSI, but why MSC MUST re-allocated new TMSI every time after location update or service access? It should be can use old TMSI, is it?

3. How load Balancing work at MSC Pool? We have 2 MSCs in one POOL here, VLR subscriber at both MSC almost same, I am still confuse how it can be like that. When subscriber perform location update using IMSI, how BSC can choose which MSC will serving this MS?


Thanks For your information

Regards,
Taufan

[boythanhnam]

Dear Core Expert

I am implementing MSC POOL currently, It's working right now, but I am still confuse with some parametes.

At my manual book mention that: "to implement MSC Pool, TMSI reallocation when location update MUST be set".

My question is:
1. For non pool MSC, what the what should I consider to choose whether TMSI REALOCATION activated or not?

2. NRI is part of TMSI, but why MSC MUST re-allocated new TMSI every time after location update or service access? It should be can use old TMSI, is it?

3. How load Balancing work at MSC Pool? We have 2 MSCs in one POOL here, VLR subscriber at both MSC almost same, I am still confuse how it can be like that. When subscriber perform location update using IMSI, how BSC can choose which MSC will serving this MS?


Thanks For your information

Regards,
Taufan
2. My question is:
MSC must re-allocation new every time after location update or service access to protect IMSI over air interface.

[inexia]

3: load balancing is done in radio. Check BSS/RNC docs for your beloved vendor.
Your BSS/RNC obviously split 50/50 on LAU without proper TMSI.
I am still not understand this statement. Why "Load Balancing" can be done in Radio part, since TMSI/NRI is allocated by MSC?


2. TMSI must be VLR specific. It ***might*** be your vendor has either
TMSI reallocation on LA change, or none.
It is NRI that matters.
I have miss understanding at this parameter before, If I set "TMSI realocation parameter" to NO, MSC will never give TMSI to MS. MSC will always use IMSI for location update ans service access :p. So it must be set yes in MSC pool

1. You need TMSI in order to have NRI.

On top: test load balancing. Emulate emergency to clean up one VLR.
We keep scripts around for normal O&M.
Be ready for suprices ....
Haha.. I really want to try this, but this MSC live already 1 week ago, I can't try anything without request from custumer. They only give me powerful access in limited time



Hi!

3: load balancing is done in radio. Check BSS/RNC docs for your beloved vendor.
Your BSS/RNC obviously split 50/50 on LAU without proper TMSI.

2. TMSI must be VLR specific. It ***might*** be your vendor has either
TMSI reallocation on LA change, or none.
It is NRI that matters.

1. You need TMSI in order to have NRI.

On top: test load balancing. Emulate emergency to clean up one VLR.
We keep scripts around for normal O&M.
Be ready for suprices ....

BR
s52d

[s52d]

Hi!

Radio nodes RNC/BSC direct to which VLR particular terminal is allocated.
VLR just give new TMSI with same NRI: but you can select % in radio.
For example, if you want 40/60% split, then 40% of IMSI based LAU are directed to one VLR,
60% to another. You can select even to ignore NRI and send all calls to second VLR,
thus emptying forst one.
SO, again, while TMSI is selected by VLR, NRI is selected by BSC/RNC (as NRI is VLR specific,
and VLR is selected by BSC/RNC).

TMSI must be used - pools does not work with IMSI. (But, IMSI based global pages works fine).

If your castomer is not testing emergency conditions: fine with them.
When they need it, they are unprepared, thus increasing downtime. As they want.

BR
s52d




3: load balancing is done in radio. Check BSS/RNC docs for your beloved vendor.
Your BSS/RNC obviously split 50/50 on LAU without proper TMSI.
I am still not understand this statement. Why "Load Balancing" can be done in Radio part, since TMSI/NRI is allocated by MSC?


2. TMSI must be VLR specific. It ***might*** be your vendor has either
TMSI reallocation on LA change, or none.
It is NRI that matters.
I have miss understanding at this parameter before, If I set "TMSI realocation parameter" to NO, MSC will never give TMSI to MS. MSC will always use IMSI for location update ans service access :p. So it must be set yes in MSC pool

1. You need TMSI in order to have NRI.

On top: test load balancing. Emulate emergency to clean up one VLR.
We keep scripts around for normal O&M.
Be ready for suprices ....
Haha.. I really want to try this, but this MSC live already 1 week ago, I can't try anything without request from custumer. They only give me powerful access in limited time

[inexia]

Hi Thanks so much :)

I never know that BSC can choose their own VLR :p. I think that function can only perform by several BSC/RNC that already support Pool configuration, is it?

At my current project, actually we SWAP an MSC (other vendor, non pool), to
POOL configuration. To do this, we consider all BSC not support POOL configuration, so A-FLEX perform by MGW. Just now I am looking for load Balancing parameter at MGW, but can't find it :p

Could you explain Load Balancing method if A-FLEX/Iu-FLEX perform by MGW?

Regards,
Taufan


Hi!

Radio nodes RNC/BSC direct to which VLR particular terminal is allocated.
VLR just give new TMSI with same NRI: but you can select % in radio.
For example, if you want 40/60% split, then 40% of IMSI based LAU are directed to one VLR,
60% to another. You can select even to ignore NRI and send all calls to second VLR,
thus emptying forst one.
SO, again, while TMSI is selected by VLR, NRI is selected by BSC/RNC (as NRI is VLR specific,
and VLR is selected by BSC/RNC).

TMSI must be used - pools does not work with IMSI. (But, IMSI based global pages works fine).

If your castomer is not testing emergency conditions: fine with them.
When they need it, they are unprepared, thus increasing downtime. As they want.

BR
s52d

[s52d]

Hi!
Different vendors, different approaches...

Anyhow, look at MSC/SGSN in pools:

How is terminal/SIM allocated particular VLR, so it can give it NRI to make sure it stays
in same VLR?
There is a lot of signalling perfomed before TMSI is known to BSC/RNC/MGW node.
This signalling is normally perfored by MSC/VLR, but for pools, it has to be done before.

When SIM card enters service area of the pool, it reports IMSI to this node. At this point,
BSC/RNC/MGW selects new VLR for this SIM card, after it is registered in VLR, it gets TMSI.
So, if your vendor implemented load sharing, it is in the point where decision is made.
In my case, it is RNC/BSC. For both MSCs and SGSN.

We did a lot of tests like : clean up one VLR or move 40% of traffic to another VLR.
Works with E///. Almost works, not really how we expected it to work.

BR
s52d















Hi Thanks so much :)

I never know that BSC can choose their own VLR :p. I think that function can only perform by several BSC/RNC that already support Pool configuration, is it?

At my current project, actually we SWAP an MSC (other vendor, non pool), to
POOL configuration. To do this, we consider all BSC not support POOL configuration, so A-FLEX perform by MGW. Just now I am looking for load Balancing parameter at MGW, but can't find it :p

Could you explain Load Balancing method if A-FLEX/Iu-FLEX perform by MGW?

Regards,
Taufan

[inexia]

Hi

I just confirm to my vendor HQ (but always take long time to ask them:p ). Because here we use tradistional BSC (existing BSC mostly not support Pool), so we use MGW to implement A-FLEX. We assign new Signaling point at MGW, and will used by BSC as their Destination point. BSC know that he only connect to 1 MSC (but actually it's connect to MGW SP).

It's exactly same what you say, when MS perform location updatae use IMSI, BSC will directly sent it to MGW, MGW will DECIDE to which MSC this location update (Depend on MSC Capcity), and the MSC allocated new TMSI containing MSC NRI

When MS initiate a service/location update (service access request/location aupdate request message containing TMSI), MGW will check NRI at TMSI to choose which MSC will handle the subscriber.

Thanks all for your reply, I will ask many case later... :D

Regards,
Taufan


Hi!
Different vendors, different approaches...

Anyhow, look at MSC/SGSN in pools:

How is terminal/SIM allocated particular VLR, so it can give it NRI to make sure it stays
in same VLR?
There is a lot of signalling perfomed before TMSI is known to BSC/RNC/MGW node.
This signalling is normally perfored by MSC/VLR, but for pools, it has to be done before.

When SIM card enters service area of the pool, it reports IMSI to this node. At this point,
BSC/RNC/MGW selects new VLR for this SIM card, after it is registered in VLR, it gets TMSI.
So, if your vendor implemented load sharing, it is in the point where decision is made.
In my case, it is RNC/BSC. For both MSCs and SGSN.

We did a lot of tests like : clean up one VLR or move 40% of traffic to another VLR.
Works with E///. Almost works, not really how we expected it to work.

BR
s52d

[dje2005]

Dears,

I have the same case in here (RNC NSN and MSC E*******), there is a MIP (MSC in Pool) activity and we realize that some LACs have very few attempts of paging through some MSCs.
We need to do a balancing between the MSCs.

Please explain in details what we have to do in order to balance the loads. it is E******* MSC and MGW.

1) which parameter/command to check/use if we want to see the subscribers distribution in the MSCs ?
2) what parameters to change and in which nodes ?

Dear experts, your fast answer will be highly appreciated.