T-1 1 0 .4 5 6 Next generation cellular netw orks Multim edia Services in Mobile and W ireless Helsinki University of Technology Telecommunication Software and Multimedia Laboratory Konstantin Moroz 16.03.2005 1
Overall structure � Introduction & motivation � RTP monitoring agents and Streaming Agents � Handover packet loss problem � Server Selection and Request � Streaming Services in Integrated Cellular/ WLAN Environments 16.03.2005 2
Introduction � Wireless environment: � Limited bandwidth & high bit error rate � Moving device -> handoffs -> packet loss � Main goal is to reduce errors in the wireless networks � Streaming services in heterogeneous networks 16.03.2005 3
� Introduction & motivation � RTP monitoring agents and Streaming Agents � Handover packet loss problem � Server Selection and Request � Streaming Services in Integrated Cellular/ WLAN Environments 16.03.2005 4
RTP monitoring � Monitoring Agent, a new type of proxy � Helps to determine if the loss took place in the wired or wireless segment [ 1] 16.03.2005 5
Streaming Agent � Upgraded version of RTP agent � Sends statistical and timely feedbacks to the sender � Timely feedbacks are ACK/ NAK packets � Usefulness of information (statistical/ timely feedbacks) � Analysis of SA timely feedbacks � Shaping point 16.03.2005 6
� Introduction & motivation � RTP monitoring agents and Streaming Agents � Handover packet loss problem � Server Selection and Request � Streaming Services in Integrated Cellular/ WLAN Environments 16.03.2005 7
8 [ 2] 16.03.2005 SA
� Available solutions: � Mobile IP � Hierarchial mobile IPv6 � Fasthandover � Main problem: these solutions require considerable changes to the IP networks 16.03.2005 9
End-to-end approaches � no change to the IP networks � suffer from considerable packet loss during handover � Trade-offs [ 3] 16.03.2005 10
Soft IP handover Main goal: not to change the existing IP network � minimizes packet losses during handover � minimizes wireless errors Techiques: � Multihoming � Bicasting � FEC 16.03.2005 11
Multihoming � more than one IP network interface -> single connection with multiple IP addresses � soft handover between two different IPs � priority 16.03.2005 12
Bicasting � encode the data stream, � split it with more diversity than the general bicasting � and send same data down the both paths. � Possible scenarious: � both links have weak signal � one of the links has a better signal 16.03.2005 13
FEC (Forward Error Correction) � In case the packet is lost on both links [ 3] FRAGMENTATION AND FORWARD ERROR CORRECTION 16.03.2005 14
FEC cont. � extend msg from k to n symbols, adding (n-k) redundant symbols. Up to (n-k) corrupted symbols within the extended msg can be recovered. Examples: � MMSP(Mobile Multimedia Streaming Protocol) was implemented and it's performance measured. FEC's impact on the quality of MPEG-4 streaming applications was evaluated.[ 3] � SCTP(Stream Control Transmission Protocol) also multihoming used. 16.03.2005 15
Problems and disadvantages of the new solution: � double connection � computational delay � no security 16.03.2005 16
� Introduction & motivation � RTP monitoring agents and Streaming Agents � Handover packet loss problem � Server Selection and Request � Streaming Services in Integrated Cellular/ WLAN Environments 16.03.2005 17
Mobility-Aware Server Selection and Request Routing in Mobile CDN Environments. � Problem � new path with different characteristics � QoS degradation in streaming media � Proposed solutions � keep track of host � different methods � SMIL (Synchronized Multimedia Integrated Language) update [ 4] � extended RTSP (Real Time Streaming Protocol) methods [ 5] � advanced techniques [ 6] 16.03.2005 18
19 [ 4] SMIL update 16.03.2005
20 [ 4] SMIL update Cont. 16.03.2005
� Introduction & motivation � RTP monitoring agents and Streaming Agents � Handover packet loss problem � Server Selection and Request � Streaming Services in Integrated Cellular/ WLAN Environments 16.03.2005 21
Integrated Cellular/ WLAN Environments � Main idea: integration of WLAN & 3G technologies � Advantage: fast access in hot-spot areas � Two basic methods for integration � Tight coupling � Loose coupling 16.03.2005 22
Tight coupling � WLAN connected to GPRS core network. � WLAN may either emulate a radio network controller (RNC) or a SGSN(Serving GPRS Support Node). � WLAN is like any other GPRS routing area in the system Interworking unit (IWU) is needed to interface WLAN to the GPRS core network. Main advantages: � mechanisms for mobility, � QoS and security in the core network can be reused. � Handover only takes place when the mobile user either enters or leaves a hotspot area. � IP address doesn't change during the handover, since the client stays in the same GGSN. � when the hotspot areas and cellular areas overlap, it is up to user to choose the handover or not 16.03.2005 23
Loose coupling � WLAN interfaces directly with the IP-PDN and has no direct interface with the GPRS core network. � WLAN and cellular network are two separate access networks. � Protocols for authentication, accounting and mobility must be deployed. � WLAN is like a visiting network to the UMTS/ GPRS core network during handover a mobile user is given a new IP address. � Seamless handover requires advanced mechanisms. � Streaming in mobile and wireless environments is an open research problem.[ 7] 16.03.2005 24
25 Tight vs Loose coupling [ 7] 16.03.2005
Relevant work: � 802.11 integrated into mobile phone � Elcotel research. Integration into Raptor smart phone [ 8] . � Lower cost & higher data rates � Viewed as complementary technology � Challenges: � Module size, weight � Power consumption � Security issues-> additional software 16.03.2005 26
References [ 1] T. Yoshimura, T. Ohya, T. Kawahara and M. Etoh, Rate and Robustness control with RTP monitoring agent for mobile multimedia streaming, Proc. IEEE Int. Conf. Communications(ICC 2002), April 2002. [ 2] G. Cheung and T. Yoshimura, Streaming Agent: A network proxy for media streaming in 3G wireless networks, Proc. IEEE Packet Video Workshop, April 2002. [ 3] H. Matsuoka, T. Yoshimura, and T. Ohya, A robust method for soft IP handover, IEEE Internet Comput. 18-24, (March/ April 2003) [ 4] T. Yoshimura, Y. Yonemoto, T. Ohya, M. Etoh, and S. Wee, Mobile streaming media CDN enabled by dynamic SMIL, Proc. WWW2002, May 7-11, 2002, Honolulu. [ 5] M. Tariq and A. Takeshita, Management of cacheable streaming multimedia content in networks with mobile hosts, Proc. IEEE GLOBECOM2002, Nov. 17-22, 2002, Taipei, Taiwan. [ 6] M. Tariq, R. Jain, and T. Kawahara, Mobility aware server selection for mobile streaming multimedia content distribution networks. Proc. 8 th Int. Workshop on Web Content Caching and Distribution, Hawthorne, NY, Sept. 29-Oct. 1, 2003. [ 7] V. K. Varma et al., Mobility management in integrated UMTS/ WLAN networks, Proc. IEEE ICC’03, May 2003, Vol. 2, pp. 1048-1053 [ 8] Master’s Thesis, Eduard Kuusmik, Wireless LAN integration into a mobile phone, Department of Signals and Systems Chalmers University of Technology Göteborg, Sweden, Conducted at Elcoteq Design Center Oy Salo, Finland, September 2004 16.03.2005 27
28 THANK YOU! 16.03.2005
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