GSM mobile-originated call in YateUCNTM – SatSite network

image describing GSM mobile originated call using YateUCN core network

Pure IP solution, any network backhaul is supported with low packet loss rates.

Doesn’t require a BSC function.

BTS and BSC functions are not geographically attached to a single MSC.

The mobile station connects to the SatSite, which makes a connection to a YateUCN’s MSC/VLR component via SIP/RTP.

The subscriber is authenticated to the network by the YateUCN using the SIM/USIM and SIP AKAv1-MD5 algorithms.

All low level, time critical signaling is confined in the SatSite and does not require any transport.

Entire SIP messages are sent over the IP network instead of multiple short messages.

Voice data is compressed and transported using the standard RTP (real time transport) protocol.

Transcoding is performed only if required. Optionally, local calls in the same cell can bypass the network completely.

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Conventional networks

image describing GSM mobile originated call in a conventional core network

Synchronous TDM-based A and Abis interfaces are required between the MSC, BSC and BTS.

Each BTS and BSC are connected hierarchically in a tree to a single controlling MSC, without failover.

Even brief disruptions of TDM links cause call failures.

Multiple small messages have to travel the entire network from BTS to MSC.

All-voice data is transcoded to G.711 even for a call between two mobile stations.

GSM mobile-terminated call in YateUCN-SatSite network

image describing GSM mobile terminated call using YateUCN core network

YateUCN includes the GMSC function, can receive and forward calls on SIP.

Doesn’t require a BSC function.

Routing to the YateUCN or any other Visited MSC uses dynamically allocated Roaming Numbers.

Calls are delivered over SIP to the SatSite where the subscriber is registered.

The SatSite pages the Mobile Station and allows it to connect to the Radio Network.

The YateUCN authenticates the subscriber using the SIM/USIM and SIP AKAv1-MD5 algorithms.

Transparent interworking with IMS, fallback to GSM.

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Conventional networks

image describing GSM mobile terminated call in a conventional core network

GMSC is usually a separate hardware function

ISUP/SS7 is used as signaling transport, voice uses G.711 over TDM.

Routing to the Visited MSC/VLR uses dynamically allocated Roaming Numbers.

The MSC sends the paging request to all BSCs and all BTSs in its Location Area.

All voice data is transcoded to G.711 even for a call between two mobile stations.

VoLTE call in YateUCN-SatSite network

image explaining aa VoLTE call using Yate IMS and HSS

Unifies the EPC layers, offering access to the interfaces required for roaming.

Includes an IMS that performs the functions of the P-CSCF, I-CSCF and S-CSCF.

Call paths and processing are similar to GSM calls, most services are shared.

Fallback to GSM can be performed in the same box.

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Conventional networks

image proving VoLTE call in conventional IMS

Several separate network functions (ENB, MME, S-GW, P-GW) are involved in the data session establishment.

Several other IMS functions (CSCF) are involved in voice call establishment.

Uses a completely different infrastructure, protocols and services from GSM.

Fallback to GSM involves complex Roaming Retry or Roaming Forwarding procedures.

SMS in GSM in YateUCN-SatSite network

image showing how SMS works in a GSM network based on YateUCN

YateUCN can send or receive SMS over different IP protocols: MAP/SIGTRAN, DIAMETER.

The SMS is exchanged with the SatSite using an IMS compliant SIP MESSAGE.

The subscriber is authenticated by the YateUCN using the SIM/USIM and SIP AKAv1-MD5 algorithms.

The SatSite deals internally with paging and all the small messages.

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Conventional networks

image showing how SMS works in a conventional GSM network

Many short messages are sent over the TDM based A and Abis interfaces.

The entire Location Area is paged for MT SMS.

SMS in LTE in YateUCN-SatSite network

image explaining SMS in LTE nerwotk based on YateUCN without CSFB

Supports IMS MESSAGE, LTE NAS tunneling and CSFB.

Except for the rarely needed CSFB, all functions are built-in.

Transparently supports MAP/SS7 and DIAMETER as transport for SMS.

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Conventional networks

image explaining SMS in a LTE conventional network using CSFB

Usually implemented using slow and disruptive CSFB procedures.

Some implementations support LTE NAS tunneling.

SMS over IP (SIP MESSAGE) requires interaction with IMS components.

Needs updated MSCs to propagate the messages received on MAP/SS7.

Infrequent DIAMETER support.

Mobility and handover in GSM in YateUCN-SatSite network

image explaining Handover in a GSM network using YateUCN

SatSite is not attached to a specific YateUCN in a given area.

Any MS can register and call through any YateUCN although it prefers the last one used.

In case of network failure the SatSite can select a different YateUCN.

Inter-MSC handover is needed only at the network edges.

SatSite units communicate and perform handover over SIP peering protocols with minimal YateUCN interaction.

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Conventional networks

image explaining Handover in a GSM network

All BTS and BSC in a Location Area connect to a single MSC, without failover.

Inter-MSC handover is required once the Mobile Station leaves the Location Area.

Handover can be performed at BSC level with moderate MSC interaction.

Mobility and handover in LTE in YateUCN-SatSite network

image explaining Handover in a LTE network based on YateUCN

Same as in conventional networks, but simpler because of YateUCN’s unified nature.

YateUCN (MME/S-GW) relocation is only required in case of failure.

Can authenticate and register LTE User Equipment over DIAMETER or MAP/SS7.

Built-in PDN Gateway can be used for Local IP Break-out or SIPTO functions.

Optional autonomous local authentication for small deployments.

CSFB support via built-in MSC proxy using Roaming Retry.

SRVCC support via built-in MSC handover.

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Conventional networks

image explaining Handover in a LTE network

Network attach causes eNodeB to select a MME which is preferred by UE for later connections.

eNodeB performs load balancing based on reported MME capacity.

X2 handover moves the UE from one eNodeB to another with minimal MME and S-GW interaction.

CSFB and SRVCC functions require extra connections to other components.