International Journal of Scientific & Engineering Research, Volume 4, Issue 11, November-2013 1375
ISSN 2229-5518
Seamless Handover in UMTS-HSDPA / WiMAX Interworking Using Proxy Mobile IPV6
Jacqueline. J. George, Mohammed Mohyeldin Siddig, Abdelrhman.O.A.Siribbal, Hind Al_jaily Mohammed, Rowa
Mohammed Ishag, Wafa Hamid Abdelrhman
Abstract— providing an automatic handover for any moving device in a heterogeneous network with different access technologies is the main aim of Next Generation Networks. Using the global mobility protocol for managing localized mobility causes a number of problems, such as long registration delay, signalling overhead and location privacy. To overcome these problems, Proxy Mobile IPv6 is proposed which can avoid tunnelling overhead over the air and provide support for hosts without an involvement in the mobility management. In this paper, we present a UMTS-HSDPA and Mobile W iMAX interworking architecture based on the 3GPP and W iMAX standards and explain the seamless inter-system handover scheme using PMIPv6 which enables the service continuity with low handover latency.
Index Terms— Proxy mobile IPv6, UMTS-HSDPA, WiMAX, Interworking, Vertical handover, handover latency
—————————— ——————————
ith the rapid growth in the number of mobile subscrib- ers and mobile devices the demand for handover be-
tween networks is becoming an important concept in mobile telecommunication, beside the demand for “anywhere, any- time, and any way”, high-speed mobile services are becoming a primary concern in our lives [1].
Recent advances in various mobile wireless generations such as IEEE 802.16d/e and Universal Mobile Telecommunications System - High Speed Downlink Packet Access (UMTS- HSDPA) and worldwide interoperability for microwave access (WIMAX), and the incessant efforts of several standards bod- ies such as IETF, 3GPP, and ITU-T appear to increase the pos- sibility of realizing mobile and ubiquitous computing envi- ronments [2]. However, many challenges still remain to be solved for achieving such a goal. The recent fundamental net- working trend has focused mainly on combining the high data rate of WIMAX with the large coverage area and low cost of operation of UMTS-HSDPA in an architecture and allow the handover of mobile subscriber between them [3].
Over the last decade “mobility management” has become an
important area of research and various new protocols and
standards have been developed. Recently, the Proxy Mobile
IPv6 (PMIPv6) [4], which is a network based mobility man-
agement protocol standard was ratified by the Network-based
Localized Mobility Management (NetLMM) working group of
IETF. PMIPv6 is a protocol that uses the same concepts as
used in Mobile IPv6 (MIPv6), but modified to operate in the
network part only instead of involving the Mobile Node (MN)
as well. PMPv6 is claimed to posses a number of advantages
over the host based mobility management protocols in use
today [5]. The main advantage of using PMIPv6 is the freeing up of the mobile host in doing any mobility related activities and thereby saving its resources.
This paper presents an inter-working architecture between two different access technologies capable of maintaining con- tinuity of an on-going session without changing the IP address of the consumer while moving in an area covered by UMTS- HSDPA and WiMAX. The architecture presented has two
main features. Firstly, it uses a mobile device capable of main- taining identical radio links simultaneously with UMTS- HSDPA and WiMAX. The device is also capable to process, monitor and compare the signals received (RSS) through dif- ferent interfaces and make decisions of handover when ap- propriate. Hence, the handover would be mobile initiated. The idea is that the user moves from one network to another when the coverage is not available or the network condition is not good enough. The second feature of this architecture is that it uses proxy mobile IPv6 at the network layer to provide net- work-based mobility management support to a mobile node (MN) in a topologically localized domain.
PMIPv6 extends MIPv6 Signalling and reuses many concepts of MIPv6 such as the Home Agent (HA) functionality. PMIPv6 introduces two new network functional elements called Local Mobility Anchor (LMA) and Mobile Access Gateway (MAG).The LMA behaves like the HA of the MN in the PMIPv6 domain. It also has additional capabilities required for network-based mobility management [6].
Figure 1 and Figure 2 [6] shows the signaling call flow of the initial attachment and the handover procedure respectively.
As MN enters a PMIPv6 domain, it attaches to an access link. After the MAG receives router solicitation (RS) message from MN, it will perform the access authentication using MN’s identity by sending a Query message to AAA server. After successful authentication, MAG gets the MN’s profile and sends proxy binding update (PBU) message containing the identity of MN to LMA on behalf of the MN. Once LMA re- ceives PBU, it performs the access authentication to insure that PBU is authorized. If both the MAG and MN are trusted, LMA accepts the PBU message, stores a binding cache for the MN and sends proxy binding acknowledgement (PBA) including the MN’s home network prefix. MAG sends router advertise- ment (RA) messages to MN on the access link advertising the MN’s home network prefix, which was given from LMA .Then
IJSER © 2013 http://www.ijser.org
International Journal of Scientific & Engineering Research, Volume 4, Issue 11, November-2013 1376
ISSN 2229-5518
the MN configure the IP address, and uses the tunnel between MAG and LMA to send or receive packet. After the attach- ment procedure is completed, the MN’s IP address remains the same while it moves within the PMIPv6 domain [6] [7].
Fig.1. Signalling Call Flow of Mobile Node Attachment Procedure
When the MN moves to the access network of a new MAG, the old MAG detects that the MN has moved away from its
Fig.2. Signalling Call Flow of Mobile Node Handover Procedure
access link. Therefore, the old MAG sends a DeReg PBU (De- Registration PBU) message to the LMA for de-registration. Upon receiving the PBU message, the LMA sends a PBA mes- sage to old MAG and waits for an amount of time, before it deletes the MN’s Binding Cache Entry [6] [7].
When the new MAG detects the attachment of MN, it obtains the MN-profile using an MN-ID after successful access au- thentication. The new MAG then sends a PBU message con- taining the identity of MN to the LMA in order to update the LMA about the current location of the MN. If that request is accepted the binding cache entry is updated with a new value which is the address of new MAG. After updating the binding cache entry, the LMA sends a PBA to new MAG, the new MAG then sends RA messages to the MN with its MN’s IP. Upon receiving the RA message, the MN believes it is still on
the home link [7].
HSDPA AND WIMAX NETWORKS
The interworking architecture between UMTS-HSDPA and WiMAX networks is shown in Figure 3. It is composed of sev- eral components:
• MN (Mobile Node): The mobile node that uses either
UMTS or WiMAX network.
• BS (Base Stations): The stations of WiMAX network.
• Node B: The base station in UMTS-HSDPA network.
• RNC (Radio Network Controller): Controls node B’s that
are connected to it.
• AAA proxy server (Authentication, Authorization and Ac-
counting unit).
• Two MAGs (Mobile Access Gateways), one is located with
an ASN-GW (Access Server Network Gateway) in WiMAX network and the other with SGSN in UMTS-HSDPA net- work.
• LMA (Local Mobility Anchor) with two interfaces: One for UMTS network through the GGSN (GPRS Gateway Serving Network), and the other for WiMAX network through the Packet Data Gateway (PDG).
• PDN( Packet Data Network ): it is a router to route the packets from one proxy domain to another [8].
Fig.3. Architecture of Integrating Mobile W imax within the UMTS-HSDPA Evolved Packet Network using PMIPv6
Handover latency is a critical factor in evaluating the hando- ver performance of one protocol. In this section, by establish- ing the system model, we give the handover latency in the interworking architecture between UMTS-HSDPA and Wi-
IJSER © 2013 http://www.ijser.org
International Journal of Scientific & Engineering Research, Volume 4, Issue 11, November-2013 1377
ISSN 2229-5518
MAX networks using PMIPv6
Tumts =
Packets
size
(3)
Figure 4 shows the system model used to evaluate the hando- ver latency in the interworking architecture between UMTS- HSDPA and WiMAX networks when using PMIPv6. In this simulation, it is assumed that the UMTS-HSDPA has a radius of 2.4 km with a bandwidth of 7.2 Mbps and that the range of
UMTS / HSDPA Bandwidth
T link: The delay in wired link between AAA, MAG and
LMA and is given by Eq.4
Tpacket : is the packet transmission delay and is given by:
each WiMAX BS (base station) is 1 km in radius with a band-
width of 70 Mbps. It is also assumed that the system is de-
Tlink =
Packets
size
( 4 )
signed to receive and transmit 1000 packets per second with size of 1000 bytes and a delay of 0.01 msec between packets. The link bandwidth between LMA, MAGs, and AAA server is
Link Bandwidth
fixed to 100 Mbps [8][9]. The path-loss and shadowing used to calculate the RSS of MN is mathematically given by Eq.1:
T packet
.
= No of
packets × delay between packets
RSS= Where:
PL(d0) − 10log(d/d0) + σ
(1)
T process: the delay of packets process in each one of the three main units AAA, MAG and LMA which is considered the same for all.
PL (d0) = the received power at a reference distance (d0). d = the distance between base station and MN.
σ = the zero-mean Gaussian random variable. d0 = is the reference distance, usually 1 km.
Fig.4. System Model
A simple analytical model shown in Figure 5 was considered for the performance analysis. The notations in Figure 5 are defined as follows:-
Fig.5. Handover Latencies
The IP handover latency can be expressed as the sum of the above latencies, more specifically, handover latency is defined as the time that elapses between the moment the layer 2 hand- over completes and the moment the MN can receive the first data packet after moving to the new point of attachment.
In order to estimate the total handover delay, based on the assumptions mentioned, the handover operation from one network to another is expressed as follow:
MN delay over UMTS network is:
UMTS delay = T umts + Tpacket + T link.
Twi max =
Packets
size
(2)
Handover signalling delay:
Signalling delay = 2 * T process + T link.
WiMAX
Bandwidth
Packets buffering delay time in LMA:
Twimax: is the packet transmission delay between Wimax
BS and MN and is given by Eq.2
T umts: is the packet transmission delay between
UMTS-HSDPA nodeB and MN and is given by Eq.3:
Buffering delay = T process + 3 * T link. MN delay over the WiMAX wireless link:
WiMAX delay= Twimax + Tpacket + T link.
IJSER © 2013 http://www.ijser.org
International Journal of Scientific & Engineering Research, Volume 4, Issue 11, November-2013 1378
ISSN 2229-5518
In order to evaluate the handover latency in the interworking architecture between UMTS-HSDPA and WiMAX networks when using PMIPv6, two cases were considered. Figure.6. shows the first case, where the MN is first attached to the UMTS-HSDPA network and then a handover to the WiMAX Network occurs. The MN first sends a request to the UMTS- HSDPA network for attachment. The mobility signaling is then done between the SGSN/MAG and GGSN/LMA on be- half of the MN, after that the LMA establishes a tunneling channel with the SGSN/MAG and the MN start transmitting its packets using the UMTS-HSDPA network link. The RSS signal is then measured each second, until the MN enters the overlapping area and the RSS becomes lower than the thresh- old value, then the handover signalling procedure starts. After successful handover the MN start transmitting its packets us- ing the WiMAX network link.
Fig.6. Packets Flow when MN Handover from UMTS/HSDPA to W iMAX
Fig.7. Packets flow when MN Handover from W iMAX to UMTS/HSDPA
Figure.7. shows the second case with the handover reversed between the two networks; the MN is now attached to the WiMAX network. The mobility signaling is done between the ASN-G/MAG and GGSN/LMA on behalf of the MN then a
tunneling channel is established where the MN start transmit- ting its packets using the WiMAX network link. The MN then enters the overlapping area and the handover signaling pro- cedure starts. After successful handover the MN start trans- mitting its packets using the UMTS-HSDPA network link.
As can be observed from Figure.6 and Figure.7, the signal gets disconnected from the MN around 0.44 sec in case of UMTS- HSDPA to WiMAX handover and 0.1257 sec in case of Wi- MAX to UMTS-HSDPA handover, resulting in packets buff- ered in LMA as the MN enters the overlap area (i.e., leaves the old network for the new network). The discontinuity corre- sponds to the period when handover procedures are per- formed, and the MN is unable to send or receive ongoing communication. It can also be observed that the delay when transmitting the packets in UMTS-HSDPA is greater than that of the WIMAX due to the narrow bandwidth of UMTS- HSDPA and the large bandwidth of WIMAX.
The objective of this paper was to implement a new mecha- nism of vertical handover between UMTS-HSDPA and WI- MAX networks; therefore, a new interworking architecture was proposed by using PMIPv6 as the mobility management protocol over the two networks.
The UMTS-HSDPA network was considered as the 3G net- work technology due to its large coverage area and quality of service compared with the old series of 3G network technolo- gies. The WIMAX is one of the 4G networks technologies, which provide high data rate up to 75 Mbps.
Due to the large coverage area and high data rate that the UMTS-HSDPA and WIMAX provide, the two networks were chosen to provide better solution for the rapid growth of de- mand for “anywhere, anytime high-speed Internet access, with respect of decreasing the cost of installation new net- works infrastructure of the 4G system.
In this paper the handover latency in the interworking archi- tecture between UMTS-HSDPA and WiMAX networks using PMIPv6 was simulated. The simulation showed that the PMIPv6 performs well and obtained a reasonable handover delay, the results also showed that the delay obtained when transmitting the packets in UMTS-HSDPA is greater than that of the WIMAX due to the narrow bandwidth of UMTS- HSDPA and the large bandwidth of WIMAX
[1] P. Vidales, J. Baliosian, J. Serrat, and G. Mapp, “Autonomic system for mobility support in 4G networks”, IEEE Journal on Selected Areas in Communications, vol. 23, no. 12, pp. 2288–2304, 2005
[2] H. Fathi, R. Prasad, and S. Chakraborty, “Mobility management for VoIP in 3G Systems: Evaluation of Low-latency Handoff Schemes”, IEEE Wireless Communications, vol. 12, no. 2, pp. 96–104, 2005.
[3] R. Koodli et al., “Fast Handovers for Mobile IPv6”, RFC 4068, IETF, July 2005
[4] S. Gundavelli et al., “Proxy Mobile IPv6”, RFC 5213, IETF, August,
2008.
[5] K. Kong, W. Lee, Y. Han, M. Shin, and H. You, “Mobility manage- ment for all-IP mobile networks: mobile IPv6 vs. proxy mobile IPv6”,
IJSER © 2013 http://www.ijser.org
International Journal of Scientific & Engineering Research, Volume 4, Issue 11, November-2013 1379
ISSN 2229-5518
IEEE Wireless Communications, vol. 15, no. 2, pp. 36–45, 2008.
[6] Yong Li, Haibo Su Li, Su Depeng Jin and Lieguang Zeng, “A Comprehensive Performance Evaluation of PMIPv6 over IP-Based Cellular Networks”, 69th IEEE Vehicular Technology Conference, 2009.
[7] Ju-Eun Kang1, Dong-Won Kum2, Yang Li2, and You-Ze Cho2,” Seamless Handover Scheme for Proxy Mobile IPv6”, IEEE Interna- tional Conference on Wireless & Mobile Computing, Networking & Com- munication, 2008
[8] Thazin Ei and Wang furong “Trajectory-Aware vertical Handover
protocol Between WiMAX and 3GPP networks”, Information Technol- ogy Journal, 9: 201-214, 2010.
[9] Doufexi, E. Tameh, A. Nix, S. Armour and A. Molina, “Hotspot wire- less LANs to Enhance the Performance of 3G and Beyond Cellular Networks”, IEEE Communication Magazine, Vol. 41, pp. 58 – 65, July
2003.
IJSER © 2013 http://www.ijser.org