Build Mobile Apps With Zero Coding
Mobile computing is characterized by many constraints small, slow, battery-powered portable devices, variable and low-bandwidth communication links. These constraints complicate the design of mobile information systems. In our work, mobile applications, especially ones that do intensive computation and communication (such as next-generation multi-medial PCS and UMTS applications), can be divided dynamically between the wired network and the portable device according to the mobile environment and to the availability of the resources on the device, the wireless link, and the access network. To demonstrate our idea, we developed a code mobility toolkit and experimented with a resource-intense mobile application. With potentially many users executing such applications, the scalability of our approach becomes extremely important. We will briefly discuss performance prediction models based on measurements and LQNs (layered queuing networks). Our results show that it is feasible to...
Chapter 12 has described the signaling between a mobile station (MS) and a mobile switching center (MSC) in a cellular (public land) mobile network (CMN, PLMN). The present chapter describes the mobile application part (MAP) of signaling system No.7 (SS7). MAP defines a number of remote operations (transactions) that support mobile telecommunications.
The main benefit for the mobile subscribers that the international standardization of GSM has brought is that they can move freely not only within their home networks but also in international GSM networks and that at the same time they can even get access to the special services they subscribed to at home - provided there are agreements between the operators. The functions needed for this free roaming are called roaming or mobility functions. They rely mostly on the GSM-specific extension of the Signalling System Number 7 (SS 7). The Mobile Application Part (MAP) procedures relevant for roaming are first the Location Registration Update, IMSI Attach Detach, requesting subscriber data for call setup, and paging. In addition, the MAP contains functions and procedures for the control of supplementary services and handover, for subscriber management, for IMEI management, for authentication and identification management, as well as for the user data transport of the Short Message Service....
Mobile code is used in several structures to support mobile applications. In Java programming language, applets are used for small applications to be installed automatically wherever they are needed and removed when their users do not need them. In the agent paradigm, small, autonomous bits of code travel to search for desired data. The mobile code is used for performance and autonomy. Agents can provide a better performance as the code moves closer to data in the network. Agent autonomy allows the user to log off or shut down the machine, and the agent that left the originator computer can continue to run even if the originator disconnects. Java RMI allows for building various distributed systems and can be used for automatic application installation or for building agent-based systems. Mobile code in RMI is used for object-oriented networked systems and it supports evolvable implementations of remote objects and new implementations of parameter and return types. Jini uses mobile...
Wireless LANs provide wideband wireless local access and offer intercommunication capabilities to mobile applications. This technology is supported by 802.11 standard developed by the IEEE 802 LAN standards organization. Wireless LANs are also provided by High Performance Radio LAN (HIPERLAN) Type 1 defined by the European Telecommunications Standards Institute (ETSI) RES-10 Group.
Another uncertainty is that wireless networks lack the bandwidth oftheir wired counterparts (Tarasewich et al., 2002). Applications that run well on a wired network may encounter new problems with data availability, processing efficiency, concurrency control, and fault tolerance when ported to a mobile environment. Limited bandwidth inhibits the amount and types of data that can be transmitted to mobile devices. Significantly improved bandwidth is clearly needed before new types of mobile applications such as Web access, video, document transfer, and database access can be implemented. Bandwidth is expected to increase rapidly over the next few years with the introduction of a new generation of wireless technologies. It is uncertain, therefore, how fast firms will follow the increased bandwidth evolution.
As the ISO usability standard suggests, context of use is an integral part that should be taken into account when conducting usability studies. However, analysis ofuse contexts for the mobile environment is significantly more complex than that of nonmobile environments. Gorlenko and Merrick (2003) outlined the three challenges that face designers of mobile applications and the usability testers.
Finding approaches to reduce power consumption and to improve application performance is a vital and interesting problem for mobile applications executing on resource-constrained portable devices. We suggested a new approach in which part of an application will be encapsulated in a mobile agent and potentially shipped for execution to proxy servers, according to the portable device and fixed host's available resources and wireless network state. To support our approach, we designed and developed a mobile object toolkit, based on Java. With this toolkit we combine JVMs on both the proxy server and the portable device into one virtual machine from the application point of view. The results showed that it is possible to simultaneously improve application performance and reduce power consumption by migrating the entire MP3 decoder to the proxy server in the case of a slow portable device and sufficient wireless bandwidth. OMA 00 Omar S., A Mobile Code Toolkit for Adaptive Mobile...
The overall architecture of H.264 AVC is similar to the other ITU-T and MPEG codecs, but a number of new features make it much more effective. It includes motion compensation with quarter-pixel accuracy and variable block sizes (from 4 x 4 to 16 x 16), an inloop deblocking filter for reducing blocking artifacts, a bit-exact DCT-like transform that operates on 4 x 4 (or 8 x 8) blocks and advanced prediction of intra blocks. The multi-picture motion compensation can use 16 reference pictures, which increases the chances of finding good matches for motion prediction. However, as delay has a severe impact on conversational services, reference frames should only be used for forward prediction. The option to use context-adaptive binary arithmetic coding increases the compression efficiency further. It works best for coding large data units at high bit rates and is less useful for mobile applications where the bit rate is relatively low and the data is segmented into independently decodable...
The remainder of this chapter briefly describes GSM-MAP, the Mobile Application Part defined by the International Telegraph and Telephone Consultative Committee (CCITT) now known as the telecommunications standards sector of the International Telecommunications Union (ITU-T) and the European Telecommunications Standards Institute (ETSI).
TCAP is used in cellular networks as well. Cellular networks use application protocols which require the services of both SCCP and TCAP. The Mobile Application Part (MAP) is one of these application protocols. What TCAP provides is management of queries and support for multiple transactions in one transmission. TCAP also provides error detection correction, segmentation, and reassembly.
An example of a IPv6-based mobility solution is the AMASE (Advance Mobile Application Support Environment) project (Jayabal, 2004). It is aimed at providing a middleware for mobile devices that will allow users to move from one network to another and still have access to rich multimedia services in a seamless manner. One of the key features of this middleware is the intelligent abstraction of the underlying networks and network resources that are handled by a module called UAL (Universal Adaptation Layer). This entity is the client part of a mobility and resource management framework, which provides the mobility function in AMASE while, at the same time, facilitating the other additional functions to be carried out, as mentioned previously. The components of AMASE are elaborated in the following section
The closest types of networks rendering a similar behavior to WSNs are WAHNs, although they have marked differences as highlighted in our discussion. Properly standardized MAC protocols designed to cater to the ad hoc and distributed nature of WAHNs have been developed and are in commercial use. Also, some of them focus on energy savings, mainly for mobile applications. These features are highly sought after in WSNs as well.
As the crossroads where behavior meets technology is inherently interdisciplinary, the search for design solutions extends beyond the design and human factors communities. While anthropologists and other social scientists study human activity and can contribute to certain aspects of design, planners and architects also offer deep insights into the interactions among people and man-made artifacts (Kaplan, 1973). A design language developed for architects (Alexander, 1977) was adapted to software (Scanlon, 2004), and the design of mobile applications (Roth, 2002). The advantage of a pattern language for design is that it captures the logic of a given context and facilitates re-use of building blocks (ranging from general design principles to actual computer code) for solutions.
The IMT-2000 effort strives to create a family of compatible standards that can be used worldwide for all mobile applications. This family is expected to support both circuit and packet switched applications and provides QoS support for multimedia traffic. This effort considered several proposals for both terrestrial and satellite communication, from which WCDMA and CDMA 2000 were selected for terrestrial communication.
Network specific signaling, MSC, HLR, and VLR hold extensions of SS 7, the so-called Mobile Application Part (MAP). Signaling between MSC and BSS uses the Base Station System Application Part (BSSAP). Within the BSS and at the air interface, signaling is mobile-specific, i.e. no SS 7 protocol is used here for signaling transport.
Waleli1 is a high tech company which utilizes the latest proven technological developments in wireless communication to bring innovations to the market. It aims to develop wireless communications to solve needs, both between people (mobile applications) and between machines and apparatuses (machine-to-machine, or M2M, communication), in a simple way.
Next in a SS7 network is the use of the SCP, which houses the databases congruent to the network. In many cases these databases interact with the HLR, VLR, EIR, AuC, and PSTN nodes. The SCP is used whenever a Global Title Translation is required, which converts numbers (800-322-2202 equates to 480-706-0912) and whenever the Mobile Application Part (MAP) is used . These services link across an SS7 interface. The GSM architecture using the SS7 protocol is shown in Figure 8-14.
The programmer should write normal Java applications, oblivious of the distributed nature of the execution environment MagnetOS will take care of partitioning and distribution of the application. The application is partitioned according to the objects that the programmer has defined. Thus, an object becomes a mobile application component. The objects are gradually distributed in the network following automatic object migration policies. In MagnetOS, two algorithms perform the automatic object migration NetPull and NetCenter. NetPull watches communication at the one-hop neighborhood level and migrates components toward links with the greatest communication. NetCenter performs the same monitoring at the network level and can migrate a component several hops at a time.
The easiest way to describe what a UMTS network is that you take an existing GSM network, add a high speed Internet connected data network, install CDMA base stations that enable higher data rates and more accurate location information, then you add more applications to make it mobile Internet-like, give fancy color screen multimedia terminal to your customers and your UMTS network is ready. You hope that higher data rates will create a new mobile application industry, that will use all the available bandwidth and you find people who are ready to pay for it. And if all goes well customers learn to call and be called by nonhuman counterparts and companies see advantages in using the UMTS network as a computer-to-computer communication path and the good times are back for everyone.
Mobile applications need to be capable of responding to time-varying QoS conditions. In the following sub-sections, we briefly describe popular tools and middleware that support adaptive mobile applications and contrast their approach to our work. Mobiware ANG 98 provides a set of open programmable CORBA interfaces and objects that abstract and represent network devices and resources, providing a toolkit for programmable signaling, adaptation management and wireless transport services. Mobile applications specify a utility function that maps the range of observed quality to bandwidth. The observed quality index refers to the level of satisfaction perceived by an application at any moment. The adaptation policy captures the adaptive nature of mobile applications in terms of a set of adaptation policies. These policies allow the application to control how it moves along its utility curve as resource availability varies. In general, it is left to the application to decide how to react to...
It is important to incorporate security controls when developing mobile applications rather than deploying the applications before and without fitting security. Fortunately, it is now becoming possible to implement security controls for mobile devices that do afford a reasonable level of protection in each of the four main problem areas virus attacks, data storage, synchronization, and network security (Brettle, 2004).
In Section 11.4 we showed the protocol architecture of the GPRS transmission and signaling plane. GPRS-specific protocols include the GPRS Tunneling Protocol (GTP), the GPRS 'Mobility Management and Session Management (GMM SM) protocol, and the Subnetwork Dependent Convergence Protocol (SNDCP). Some GSM protocols, such as the Mobile Application Part, have been extended for use with GPRS.
To support our approach, proxy servers need to be deployed throughout the access network, which could be a large provincial or national cellular network. On the one hand, one could envision an architecture where each wireless cell provides dedicated proxy servers, resulting in relatively little concurrent use of an individual server but inducing a high handover overhead and costs. At the other extreme, we could provide only one or very few proxy servers that support applications in many different wireless cells, reducing the handover overhead but requiring more powerful servers. With potentially multiple thousands of users executing resource-intensive next-generation mobile applications, the scalability of our approach becomes extremely important. To explore this issue, we started to
One of the paradigms of video coding is to take advantage of temporal redundancy between frames to make the coding as efficient as possible. This is particularly true for low bit rates and qualities characteristic for mobile applications where inter-frame prediction plays a crucial role in the coding process.
The signaling architecture between SGSN and the registers HLR, VLR, and EIR (Figure 11.12) uses protocols known from conventional GSM (Section 7.3) and partly extends them with GPRS-specific functionality. Between SGSN and HLR as well as between SGSN and EIR, an enhanced Mobile Application Part (MAP) is employed. The exchange of MAP messages is accomplished over the Transaction Capabilities Application Part (TCAP), the Signaling Connection Control Part (SCCP), and the Message Transfer Part (MTP).
Although CDMA has been known for several decades, only in the last two decades has interest peaked regarding its use for mobile communications because of its enhanced performance compared to standard TDMA and FDMA techniques. Greater capacity, exploitation of multipath fading through RAKE combining, soft handover, and soft capacity are some of CDMA's advantages (Viterbi, 1995). The first commercial CDMA mobile application was IS-95 (1993). The real boost ofCDMA applications, though, was the adoption of the WCDMA air interface for UMTS.
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