Research Proposal: Wireless System Integration and 4G, 3G

Abstract
It is evident that every generation of the wireless network tries to satisfy the increasing demand for more bandwidth.Wireless networks are very popular with many people and the bandwidth provided by wireless LANs as well as wireless computing can be enhanced through integration with 3G, 4G, and 3GPP systems executed at a particular level. This paper presents a research proposal on the integration of wireless systems at the core network level comprising of both 3G and 4G components. As a result of this, service integration turns to be powerful and easy to execute. The system does not rely on the critical latency of vertical handovers and the users feel a system providing services in a unique way. In order for this to be possible, a few modifications will have to be done on the current 3GPP, and a 4G core network to accommodate the wireless networks. The architecture on focus in this paper uses GPRS as the main network and then followed by integration of Wireless LANs as secondary networks, to be used on the basis of availability.The handoff mechanism is so designed as to facilitate seamless handoff and provide flexible choices of the network for switching, while maintaining transparency to the mobile node. To ensure interoperability with the existing infrastructure, the handling of mobility should be completely transparent to the protocols and applications running on the mobile node. Vertical Handover thereby is seen as a key feature to allow for interoperability. The sessions on these secondary networks can wither away disconnection periods strengthening the seamless provision of service to users.

(Key words: 3GPP, handover, 3G, 4G, WLAN, seamless, core network)

Introduction

There have been an increasing number of internet users, both corporate and home, caused by evolution of high bandwidth, IP-based applications like Multimedia Messaging Applications and Voice over IP services and applications. Managing such complex networks has resulted in significantly high network operating expenditures and a lot of time wastage.
There is a high pressure for high network availability and reliability. Employee and customer expectations are rising, demanding real-time information anytime and anywhere, and collaboration beyond traditional borders.
This has created a strong demand for wide-area broadband access to IP services and more so Market innovations and competitions have opened the gates for new entrants. In the 21st century, enterprise businesses are being transformed to meet the evolving challenges of today’s global business economy. New innovations and new business models are enabling new kinds of productivity, competitive advantage, revenue growth, and efficiency that drive the top line and the bottom line. Another fact is that over the years, telecom networks have become increasingly heterogeneous and complex, with multiple vendors, applications and technologies. In such a competitive environment, balancing profitability with service quality becomes crucial leading to more developments. Wireless Systems Integration (WSI) services help telecom service providers, network equipment manufacturers and other telecom players to continually enhance the network infrastructure capabilities to optimize network management operations. This paper is to offer a complete solution to the cellular industry, a solution that ensures a more secure communication environment, efficiency, innovation and cost-effectiveness, helping in the improvement of the bottom lines significantly.
Universal Mobile Telecommunication System (radio frequencies used by third Generation (3G) wireless Universal Mobile Telecommunication System networks) and its predecessor GSM/GPRS (Global System for Mobile Communication/General Packet Radio Service) are cellular systems that provided IP-services nearly everywhere. However, these systems are faced with bandwidth limitations because of their requirements on coverage. The Wireless LANs (WLANs) come in as essential add-on to provide to enhance the available resources (Frodigh, 2001). A WLAN typically extends an existing wired local net work area. WLANS are built by attaching a device called the access point to the edge of the wired network. Clients communicate with the AP using a wireless network adapter similar in function to a traditional adapter. The technique of integrating these systems is being developed, and this paper discusses how the integration can be implemented to allow new services for the users, and continue to support the already existing systems.
Some of the researches done earlier propose a wholesome integration of WLANs in the architecture of the cellular system (tightly coupled) or do the integration in such a manner that they will be loosely coupled. The former does not enlarge the type of services that are offered by the current cellular architecture framework while the latter presents a hardship in providing a real sense of service integration amongst the many access networks available.
The integration of cellular networks and wireless local area networks (WLANs) aims to take the advantage of the coverage-complementary characteristics of both wireless networks. The Wireless Integration is a defense-in-depth approach that encompasses the mobility services. Mobility is a critical service for individuals and for enterprises, offering greater flexibility, and enabling increased productivity, through pervasive access to network resources and applications.

Due to increase in users the applications would obviously require quality of service (Qos) and as well offer a guarantee e.g. the guarantee of the voice call and that of internet operations.
This paper proposes the necessity of admission control is in order to limit the number of connections in a network in a local area. A connection request can no doubt be blocked if the minimum bandwidth requirement cannot be satisfied. In this research paper, the integration of the cellular/WLAN system with resource sharing capabilities is proposed. This paper analyzes two admission control algorithms, namely: cutoff priority and fractional guard channel. The admission of step-by-step problem-solving procedure consider new connection requests, requests due to either horizontal ongoing call or data session from one channel connected to the core-net work to another channel or vertical handoff. If one access network does not have enough resources to support a handoff connection request, the request will be transferred to another network. This paper proposes an analytical model and determine the new connection blocking, handoff dropping probabilities of this integrated cellular/WLAN system. Performance improves significantly when resource sharing is allowed between different wireless access networks.
This is a proposal for a full research on a solution based on an integration performed at core network level amongst the major components like the Serving GPRS Supporting Node. This kind of system can be applied in various business scenarios, and not only in a 3GPP operator owned WLAN infrastructure. This approach maintains a user session and does not depend on the precise Radio Access Network (RAN) in use, claims that vertical handovers (between RANs) are not needed, and RAN switch can better be performed at the core network level (in the UMTS sense (Buddhikot et al, 2003).
Each of the User Equipment (EU) can maintain at least one IP session over a specific RAN and can use the session always, even when located out the area covered by that RAN (through use of other active RANs). The need for services to access core network-level information to improve the way they use the communication links to the UE, handle and adapt to UE mobility, and connected periods (at instances where UE is inside the coverage of a WLAN). Only slight (software) modifications to the current 3G core network is needed in order to implement the system.
Hypothesis
In today’s world, the cellular network is everywhere, covering the whole of the populated areas of the globe. Chances are that there will be no other radio network system with such coverage of the area. This means that any other network will have dark areas, and supporting users in these networks alone is not effective in the long run. Moreover, the UEs have two or more wireless interfaces that work simultaneously, and the WLANs can be owned by private organizations who have agreed to the 3GPP system operators or under the ownership of the operators themselves. Authentication, Authorization and Accounting (AAA) instructions between 3GPP systems and WLANs are almost being approved (3GPP, 2003), and assumptions to that effect will be made in this paper.
802.11b (WiFi) and CDMA2000 (3G cellular) interfaces for connection to the Internet and wireless data applications. 802.11b provides reasonably high speed (up to11Mb/s) communication, though limited in range. CDMA2000 provides slow speed high cost communications, but coverage is nationwide and reliable. These technologies are complimentary. By combining them, it is possible to achieve high speed communications within certain hotspots, while continuing to maintain reliable nationwide coverage outside the hotspots.
Seamless handoff is the ability to switch between different technologies like WLAN and CDMA2000 without requiring any input from the user. This paper discusses such a seamless handoff that allows for the best connection to be used, while not restricting the user to the drawbacks of the connection. It also provides the ability to change connections should a better one become available. The architecture and design of the solution is to be such that switching access technologies should be fast, invisible to the user and occur whenever necessary with minimal impact to any of the user sessions.
This service extends the infostation model presented by the cellular network integration. Users at home use the GPRS interface to commence a service of downloading some bulk data. A user who is on his way to work has the system trying to use the WLAN RAN for the delivery of the data. In the end, all the data will be have been transferred. GPRS as a packet service is also considered in both 4G and 3G systems standardized by 3GPP.
The cellular network is made possible due to a number of technologies, some of them being the 3G and 4G networks that have varied unique features that facilitate communication. 3G Wide Brand Wireless Network is applied so as to increase clarity and offers perfection just as like one talks in real life. The data that is directed to the technology known as packet switching. Voice calls are managed using circuit switching. It is a quite complicated form of interaction. Moreover, to the verbal communication, it is comprised of data services, availability to video. The 3G works at a range of 2100MHz with a bandwidth of 15-20MHz. The service it provides is of high speed.
Using the 3G service, we are able to acquire a number of new services like global Roaming. Similarly, this service is able to offer Wide Band Voice Channel which makes it possible for the world to be contracted to a tiny village as communication is made easier and data is sent at a fast rate. Greater significance is accorded to the clarity of voice when people communicate with no noise, or distractions.
The 4g, on the other, hand offers high internet speed for mobile services reaching 100MPS which is much higher than the 3G. This generation offers added features like Multi-Media papers and television programs that are clear. Additionally, data is sent at a faster rate. These technologies among others have made data communication much easier and effective.
Objectives of the Study
The main objective of the research is to carry out an in-depth study on how wireless networks can be integrated seamlessly into the already existing 3G, and 4G core network. The theoretical framework of the systems needs to be enumerated, and the practicability of the procedures underlined will be outlined. The study aims to establish the advantages of doing the integration, as opposed to having the two systems working in parallel or having them loosely coupled.
Complementary characteristics of WLAN (faster, short distance access) and CDMA2000 (slower, long range access), it is compelling to combine them to provide ubiquitous wireless access. Such integration can bring significant benefits to service providers and end-users. WWAN (CDMA and GPRS) service providers can increase their customer base by offering WLAN as a value-added service. Such integration will bring a larger user base to WLAN service providers from the partner CDMA network. The customers will benefit from greater coverage, higher data rate and lower overall cost. The handoff solution for seamless mobility, thus, plays a critical role in providing the needed integration between heterogeneous networks to benefit customers. From the user’s perspective, the following are required objectives to achieve seamless mobility:
• Automatic switching/handoff from one wireless access network to another based on criteria such as signal strength, and location.
• Complete network transparency at the IP layer: the user should be able to attach to the new local network without any user intervention.
• Application session persistence.
There are several other classes of applications which would benefit tremendously from seamless mobility. There is a large set of applications which fall in this class. Given below are some such critical applications:
• Applications where the user needs to be actively connected: e.g. audio and video conferencing.
• Applications where the user needs to be reachable: e.g. Voice over IP.
• Applications involving a database access: e.g. reading, writing or updating a database record.
With increase in wireless data speeds observed in the local and wide area wireless networks, it is envisaged that there will be a wide demand for these kinds of applications.
Theoretical Framework
In the past periods, cellular operators have made great advancement in data traffic because of the high speed networks and data intensive devices with a growth anticipated in the future period. Wireless Networks is a stables and popular technology, and is getting common in the cellular devices. The wireless spectrum is unlicensed and accessible. The technology is hence well places to uphold this data growth through enlarging, complimenting and steadying 3G/LTE macro exposure.
Session mobility that is there in wireless and cellular networks, preserving IP address, has been of great appeal for a long period. The desire for data traffic and pressure on huge networks is on the rise and motivating the need to enable this.
It is to a great extent of great appeal to the end user and the service provider to be able to seamlessly shift an IP session in cellular access and Wi-Fi access. This attribute makes it possible for complicated mobility aspects like Multi-Access PDN Connectivity and IP Flow Mobility as stated in 3GPP.
This section will focus on the theoretical aspect of the WLAN access to mobile operators to offer mobile network access. This makes it possible for the clients to apply their mobile tools’ WLAN access interface and the ‘connection manager’ client to direct traffic back to the operator’s packet network. Therefore able to access the mobile operator’s services and be able to acquire access to the public internet using the mobile operator. The task undertaken by the mobile operator comprises the user place routing and control panel abilities involving backend support for authentication, authorization and accounting series. This will make it possible for access control and billing for the WLAN service. In such a case, the end user’s tool is allocated an IP address by the operator and any desire for legal involvement of user traffic would be placed on the mobile operator.
In designing the theoretical framework of this research proposal, there are a few possibilities to consider.
1. The first possibility is that the wireless networks are part of the cellular network as an ordinary cell in the GSM/GPRS network. This network would predict the movement of the user through the use of the cell information and could schedule the sending of large bulks of data on the availability of a hotspot (Frodigh, 2001). However, the implementation or setting up of such a facility at the network level may be complex because there is no adequate relevant information. Furthermore, lack of bandwidth might be experienced by users just because he/ she are in a location where they might have stepped out of the network coverage area unless applications have knowledge of the differences in cells and adjust to specific cell data rate conditions.
2. The second possibility is that high bandwidth cells are seen as unique and special cells, which means that they are not integrated in the cellular system and have a special and direct connection to a packet data network. The user has knowledge that he is using a different interface and that they are moving out of coverage is easy to be detected.
There are options for WLAN integration covering both possibilities which are stated herein. The tightly coupling option explains that cells must be integrated at a low level, offering an interface compatible with all the 3GPP protocols that have been laid out (Steem & Katz, 1998). In addition to the shortcomings listed above there are disadvantages such as the fact that WLAN has to be owned by the 3GPP operator so as to avoid strong exposure of core network interfaces, cell displacement and configuration demands, carefully designed network planning tools and WLAN integration become complex to accomplish. Moreover, there are many control procedures anchored on configurational parameters such as Cell ID, Routing Area (RA), UTRAN Registration Area (URA), and many more as well as WLAN cells are required to comply with them. Furthermore, the paging procedures and handovers including vertical handovers are required to be defined clearly, and some technologies such as IEEE 802.11 are not properly optimized to increase their speed (Frodigh, 2001).
This option makes an assumption that there is a WLAN gateway found on the WLAN network bearing functionalities of a Foreign Agent, AAA relaying, firewall, and billing. Furthermore, its connection to the 3GPP core occurs through the GGPRS (Gateway GPRS) Support Node. It is only sensible to implement the project using this option with dual-mode user Equipments since a vertical handover to Wireless LANs will disconnect the UE from all the functionality presented by the cellular networks. The major advantage with this merit is that high speed data and other traffic are never injected into the 3G or 4G core network. The major disadvantage is the degree of integration since WLAN networks under this option are handled in an independent manner and used on the basis of availability by users, of which, who must stay within the same coverage of the cellular network. The other option is the loose coupling, which operates opposite of the tightly coupled integration.
Typically, a WLAN network is user and also system preferred higher priority network due to the characteristics of larger bandwidth at a lower cost. Thus, when a user connected to a WWAN (CDMA2000) network, steps into a WLAN area, he/she would like to change the connection to WLAN to obtain a possibly larger bandwidth at a lesser cost. The signal strength of the higher priority network in the descending order is monitored continuously for its availability.

The algorithm provides two trigger points that decide the switch over:
• Availability of a stable WLAN
• Decay/loss of the WWAN signal strength
The network is periodically polled to detect the availability of a stable WLAN signal. If the signal strength is sufficiently good (above the required threshold), the connection is switched to the WLAN network. The list of preferred WLAN networks, if such a list exists, is similarly polled in the order of descending priority for reliable signal strength to identify the candidate target network to switch to. This is to ensure that the WWAN to WLAN handoff is not only dependent on WWAN signal strength. In scenarios such as where the WWAN signal strength decays, a similar algorithm as described in WLAN-WWAN handoff is performed which uses multiple thresholds so as to be able to ascertain the signal strength.
The WLAN has smaller coverage. Thus, when the user steps out of a WLAN area, the non-availability of the WLAN which has the required signal strength for data transmission is to be detected quickly and the connection is to be switched to the WWAN (CDMA2000) seamlessly. Based on the analysis of the network behavior, a predefined threshold value for the signal strength is fixed. The handoff is made up of a two step procedure with two threshold values driving the handoff decision. When the user is in WLAN, the signal strength of the WLAN is sampled periodically. Once the signal strength is less than the signal strength value corresponding to the higher threshold value S1, intensive sampling begins. If the signal strength is consistently less than S1 for a certain period of time, it is recognized as a potential situation for handoff, and the next higher priority network in the order of network priorities is scanned. If the network scanned has the necessary signal strength, a connection is made immediately to that network. Otherwise, the next higher priority network(s) is/are scanned in the decreasing order of priorities. The signal strength value is then continuously compared with the second threshold value S2 of a lower signal strength. If the signal strength is lower than S2, a switch is made to the next preferred network that has the necessary signal strength. If any of the above conditions fails to occur, no switchover happens, as long as the preferred network’s signal strength is consistent.
Research Methodology
This research will involve the thorough study on the issue integration of wireless networks in the 3GPP core network comprising of 3G and 4G components. A detailed study will be done on the network design parameters that are required for the integration process. Various options introduced in the theoretical framework section will be enumerated in a lot of depth so as to establish the best choice for the implementation of the project. It is expected that when the whole research has been done, the information on the design parameters that will be collected should lead to a practical implementation.
The research shall involve doing case studies of various projects that have been implemented earlier and then fine-tuning the parameters or values to achieve the seamless integration that is desired of this research. 3G networks have been widely implemented in many countries across the world. However, 4G has only been implemented by few major operators such as AT &T (Steem & Katz, 1998). This will provide an opportunity that to come up with research findings that can be used for integration with the 4G even as its implementation gathers pace or momentum. A mixture of different methodologies should be used comprising of quantitative and qualitative techniques will be used to gather the data during the time of the research, and the results will then be analyzed accordingly.
Additionally, the methodologies offers several ways of hindering negative issues from arising. The methodology safeguards against potential conflicts that may arise while using the technologies. The operators have the ability to define the policies with regard to a wealthy base of network subscriber attributes that can be accessed on the ANDSF server. This server is in line with the OMA-DM abilities and 3GPP objectives. It can be able to offer real-tie load balancing with regard to network aspects which additionally upholds roaming and home networks. The methodology is dynamic and can be increased to comprise added features of desire to the operators.
On a general sense, this methodology can be used in local EUs, HS2.0 acquired data or 3GPP network data distributed to the UE. As opposed to ANDSF policy that is used based on the assessment of Validity region and Time, policy could similarly be appropriate for certain networks congestion points and other elements. To apply and to make it effective, it calls for a direct growth of the 3GPP.
Conclusion
The increasing mobile broadband data traffic controlled by a high end mobile devise users offers a number of challenges to the operators in getting the demand satisfied. A number of operators offer a real opportunity to look into the challenge through leveraging the prevailing Packet Core and Evolved Packet Core model to integrate user-plane traffic from wireless access. Through offering a stable selected client’s mobile broadband traffic for the network and internet wireless access points, operators are able to do away with congestion of the cellular and backhaul networks. This will lead to a reduced desire for capital use and similarly is useful in reducing the price of operation.
The integration of the wireless infrastructures done at the 3GPP core network level appears to be a simple and executable model. First, as most of the control features already exist, they can be nonexistent in other networks. Secondly, the details of the secondary networks are not managed at a core level, and finally because it specifies an environment where new features and services can be incorporated and implemented in the core network. New modules at the core level with standard (and protected) programming interfaces have been added, and this can lead to new possibilities to explore terminal mobility. This is an issue that is yet to be developed. Seamless handoff is a suitable technology for the currently available Internet connectivity mechanisms and real-time IP based applications like multimedia and Voice over IP. It enables users to utilize the best connection while being able to switch the connection should a better one become available or should the existing one fail to perform as intended. This would be of great benefit to mobile internet and data users, as they could begin an operation from a high speed base station or high bandwidth low cost local access wireless network, while continuing the operation as they move around to wherever they may be going in whatever network coverage available.
Given the complementary characteristics of WLAN (faster, short distance access) and CDMA2000 (slower, long range access), it is compelling to combine them to provide ubiquitous wireless access. Such integration can bring significant benefits to service providers and end-users. WWAN (CDMA and GPRS) service providers can increase their customer base by offering WLAN as a value-added service. Such integration will bring a larger user base to WLAN service providers from the partner CDMA network. The customers will benefit from greater coverage, higher data rate and lower overall cost. The handoff solution for seamless mobility, thus, plays a critical role in providing the needed integration between heterogeneous networks to benefit customers.
References
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Ajay Rajkumar, “Mobile-Initiated handoff Amongst Disparate WLAN and Cellular Systems”,
3GPP2-WLAN Interworking
C.Perkins ,RFC 2002, “IP Mobility Support”