femtocell synchronization a nalysis
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Femtocell Synchronization A nalysis. Rock Xie. HUAWEI TECHNOLOGIES CO., LTD. 3GPP Structure for Femtocell. - PowerPoint PPT PresentationTRANSCRIPT
HUAWEI TECHNOLOGIES CO., LTD.Page 1
Femtocell Synchronization Analysis
HUAWEI TECHNOLOGIES CO., LTD.
Rock Xie
HUAWEI TECHNOLOGIES CO., LTD.Page 2
3GPP Structure for Femtocell
• The 3GPP TR23.830 report defines the architecture aspects of Home NodeB
(3G UMTS) and Home eNodeB (4G LTE). The HNB represents the femtocell
base station and HNB GW represents the femtocell gateway. The iuh is the
interface specifying the communication between the gateway and base
station.
HUAWEI TECHNOLOGIES CO., LTD.Page 3
Femtocell Forum Structure for Femtocell
• The Femtocell Forum also provides a reference model very similar
to 3GPP
HUAWEI TECHNOLOGIES CO., LTD.Page 4
The challenges in Femtocell synchronization
The Femtocell network architecture shows that a publ
ic network is used to establish the connectivity betwe
en the femtocell and core network elements, This pre
sents a set of unique challenges:
• Femtocell synchronization security
• Femtocell synchronization connectivity
• Femtocell synchronization network scalability
HUAWEI TECHNOLOGIES CO., LTD.Page 5
Security Issue• The security is mandatory since the Gateway and Clock server communicate to
the Femtocells via a public backhaul broadband connection (also known as the
3GPP iuh interface or Femtocell Forum Fa interface).
• The important point worth noting is the large number of Femtocells that might h
ave to be served, as well as the additional bandwidth overhead IPSec represen
ts to the offered load (bandwidth consumption) of synchronization messages.
• The 3GPP has considered some of the security aspects with respect to synchro
nization performance. The [3GPP.33.820] report lists the following:
1. it may be possible to leave some of the messages unprotected, but there mig
ht be security risks. Care should be taken in considering which messages are
protection or not.
2. there may be bandwidth, delay and delay variation problems if all the messa
ges (eg., [IEEE1588]) are to be protected.
3. if delays become excessively long, reliance on internal clock might be import
ant and requires further investigation.
HUAWEI TECHNOLOGIES CO., LTD.Page 6
Connectivity Issue
• The Home GW provides Internet sharing for home devices. One of the
challenges is to define the end-to-end connectivity model between the f
emtocell and clock server when a function such as network address tra
nslation (NAT) is present within the Home GW.
• network address translation (NAT) protects the internal home network,
but prevents the direct connection between devices sitting in the home
network and devices that are outside (reachable through the public Inte
rnet). With respect to synchronization, this could limit the ability of a fe
mtocell to communicate directly to a Clock server. Therefore, some me
chanism to handle NAT translation and to guarantee proper flow of syn
chronization messages should be provided.
HUAWEI TECHNOLOGIES CO., LTD.Page 7
• The femtocell network could easily extend to millions of devices and th
e offered load of synchronization messages (bandwidth consumption) c
ould become quite large when unicast addressing is used.
• The scalability issue could impact the clock server throughput but more
importantly could increase the difficultly in capacity planning and place
ment of clock servers in the network
• The use of load balancing techniques might be beneficial to help in syn
c capacity planning but might impact performance. The use of multicast
technologies currently being developed might present opportunities to r
educe the bandwidth consumption of synchronization messages and to
considerably increase the number offemtocells a server can support.
Scalability issue
HUAWEI TECHNOLOGIES CO., LTD.Page 8
1. The use of IPSec links in public networks could degrade the transport of synch
ronization message and its performance. In order to reduce the impact of secu
rity issue in public networks, it is possible to leave some of the synchronization
messages unprotected. Caution should take place on the use of IPSec and sy
nc performance.
2. Synchronization messages traversing Network Address Translation (NAT) func
tions need to be considered, in order to guarantee proper connectivity between
a Clock Server and Femtocell.
3. Scalability aspects (large number of femtocells), bandwidth consumption and t
he placement of clock servers are important as the network architecture need t
o be developed.
4. If TICTOC intends to develop some form of synchronization profile covering m
obile backhaul for instance, then the aspects of femtocell should be taken into
account.
Conclusion
Thank You
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