A method for perfoming mode-agile communications during a communications session is disclosed. A communications terminal device (104, 118, 124B, 124A) supporting muliple modes of access is configured to detemine when, during a session involving a first mode of access communi- cations, a second mode of access is available and is to be used for subsequent communications for the session. The communications terminal device (104, 118, 124B, 124A) initiates or controls switchover from one mode of access to another.

Fixed-mobile communications with mid-session mode switching

With the development of mobile communication and Internet technology, there is a strong need to provide connectivity for roaming devices to communicate to other communication end point in the Internet at any time and anywhere. The key issue of this vision is how to support mobility in TCP/IP networks. In this paper, we review the TCP/IP protocol stack and analyze the problems associated with it in a mobile environment. We then investigate the mobility support techniques and existing solutions to provide mobility support in the Internet. We classify the proposed solutions based on the protocol layers and present examples for each category. We also provide a comparison of the different solutions belonging to different categories and in the same category, including their advantages and disadvantages, and conclude that there is no single solution perfectly addresses mobility support for the Internet. We conclude this survey with a recommendation of features that need to be satisfied in Internet mobility support.

A review of mobility support paradigms for the internet

This paper describes the session initiation protocol (SIP) based mobility in IPv6 and its performance in our laboratory testbed. For real-time mobile multimedia communication, we use SIP for signaling protocol as well as for supporting terminal mobility. While performance study for real-time mobile communication refers to several factors and their measurements, we analyze here only the handoff delay due to node mobility. In particular, we are interested to examine the delay incurred when a mobile node moves to a new link and perform the duplicate address detection (DAD) and router selection, and analyze the delay in each case. We notice that the IPv6 Linux implementation provides substantial amount of delay during node movement, which severely affects the performance of real-time applications. Therefore, we modify the Linux kernel and compare with the unaltered one. Finally, we conclude that a faster handoff is achievable in SIP based terminal mobility with intelligent modifications to unaltered Linux kernel.

/pdf/handoff-delay-analysis-and-measurement-for-sip-based-33uh09sq5s.pdf

Handoff delay analysis and measurement for SIP based mobility in IPv6

This work presents a systematic study of millimetre-wave, low-noise, widely-tuneable differential Colpitts VCOs A design methodology was developed and validated experimentally over thirteen different varactor-tuned (VCO) and fixed-frequency L-C oscillators spanning the 30-GHz to 122-GHz frequency range All circuits employ accumulation-mode n-MOS varactors, and multi-turn on-chip inductors The 35-GHz and 60-GHz oscillators achieve phase noise of -1127 dBc and -104 dBc/Hz, respectively at 1-MHz offset and deliver +4 dBm differential output power while a push-push implementation demonstrates 15-GHz (21%) tuning range from 635 GHz to 785 GHz A directly-modulated, 65-GHz binary phase shift keying (BPSK) transmitter is also implemented

https://www.eecg.toronto.edu/~sorinv/papers/chihou_csics_04.pdf

SiGe BiCMOS 65-GHz BPSK transmitter and 30 to 122 GHz LC-varactor VCOs with up to 21% tuning range

Session Initiation Protocol (SIP) was standardized for real-time applications and extended to support terminal mobility by Internet Expert Task Force (IETF). However, SIP terminal mobility suffers from the considerable handoff latency which is unsuitable for the real-time communications. In this paper, we propose Predictive Address Reservation with SIP (PAR-SIP) which decreases handoff delay by proactively processing the address allocation and session update using link layer information of wireless networks.

https://academic.csuohio.edu/yuc/papers/MobiWac04.pdf

Link layer sssisted mobility support using SIP for real-time multimedia communications

In an effort to realize wireless Internet telephony and multimedia streaming in a highly mobile environment a testbed emulating a wireless Internet has been built. This allows the setting up of multimedia calls between IP mobiles and integration between IP and PSTN end-points in a wireless environment. Different functionalities and components involved with the wireless Internet streaming multimedia have been prototyped and experimented in the testbed. These include signaling, registration, dynamic binding, location management as well as supporting the QoS features for the mobile users. This paper describes some of the components of the testbed and highlights the experiences while building this testbed which could be beneficial to some who plan to build a similar testbed to realize several features and capabilities of Mobile Wireless Internet, before actually bringing to the market.

/pdf/implementing-a-testbed-for-mobile-multimedia-1fjx0e7fpu.pdf

N. Nakajima

Papers

Implementing a testbed for mobile multimedia