Application Analysis of P2P Technology in mobile Internet Environments

P2P (peertopeer, peer-to-peer) technology, it is an application mode that shares resources and services through direct exchange between systems. In the P2P network structure, each node has the same status and has the dual functions of the client and server, and can serve as both service users and service providers. P2P is not only a technology, but also an idea that embodies the essence and characteristics of Internet equality, openness, and freedom.

Over the past few years, P2P applications represented by Bt and eMule have developed rapidly, and P2P-based instant communication, streaming media, and Internet IP phones have also developed rapidly, p2P applications have already exceeded Web applications in the fixed Internet, accounting for more than 50% of the fixed Internet traffic. In the current mobile Internet environment, mobile P2P applications are not yet implemented due to network and terminal restrictions. However, with the continuous development and evolution of mobile networks, as well as the increasing processing capability of mobile terminals, P2P technology and services will gradually extend to the mobile Internet. This article will discuss the application of P2P Technology in the mobile Internet environment.

Main features of P2P Technology

The essential difference between P2P technology and the client/server structure that currently occupies the dominant position in the network is that there is no central node (or server) in the network structure ). P2P technology has four main features.

(1) decentralization. A pure P2P network has no central service nodes, and all the peers are both clients and servers, which is one of the most essential features of P2P. In the P2P technical structure, the significance of the center is greatly weakened or even completely disappeared. The decentralization feature is fully reflected, and the flattening feature of the network structure is further highlighted. Due to the difficulties in implementation and management caused by completely non-centralization, many P2P applications adopt a hybrid model.

(2) scalability. Scalability is considered to be one of the most important characteristics of P2P networks. In theory, P2P networks can be expanded infinitely. EMule currently has tens of millions of users worldwide. The number of Bt users exceeds that of eMule, and it is still growing rapidly.

(3) robustness. The P2P network architecture is inherently attack-resistant and highly fault-tolerant. Because services are distributed across nodes, some nodes or networks are damaged, which has little impact on others, such as the failure of the central node in the traditional network structure that causes almost no service breakdown.

(4) cost-effective. The P2P architecture can effectively use a large number of common nodes distributed on the Internet to distribute computing tasks or storage data to all nodes and use idle computing capabilities or storage space, to achieve high-performance computing and massive storage, you can use a large amount of idle resources in the network to provide higher computing and storage capabilities at a lower cost.

Based on the above features, typical P2P technology applications include file and content sharing, such as Napster, eMule, BT, distributed computing, and storage sharing, for example, SETI @ Home, avaki, and popularpower; Collaborative processing and service sharing platforms, such as JXTA and netmyservice; communication and collaboration, such as Skype, MSN, and OICQ.

P2P application implementation in mobile environments

Structure and features of mobile Internet

The logical structure of mobile Internet based on GPRS, edge, and WCDMA is shown in 1. The main group network elements include sgsn and ggsn, and the main interfaces include gn and GI. Sgsn is connected to the wireless subsystem and core network grouping domain, and is connected to ggsn through the Gn interface. ggsn is connected to the external data network through the GI interface.

Figure 1 logical structure of mobile Internet

Compared with the fixed Internet, mobile networks have some unique mechanisms and features, which may affect the application and development of P2P Technology in mobile Internet, mainly in four aspects.

(1) the GPRS, edge, and WCDMA wireless data channels adopt time-division multiplexing for upstream and downstream symmetric configuration. However, due to the characteristics of mobile Internet applications, and some mobile terminals adopt asymmetric data transmission methods (2 + 1 or 4 + 1), the upstream and downstream traffic on the mobile Internet is significantly different. Statistics show that the ratio of data traffic in the middle and lower lines of the GPRS network to upstream data traffic is about 4.5: 1, and the proportion reaches 6.4: 1 After edge is activated, the relatively idle uplink channel objectively facilitates P2P applications of file and content sharing classes.

(2) GPRS group business channels can use CS-1 ~ The maximum transmission rate of CS-4 is 171 kbit/s. Edge uses 8 PSK (8 Phase Shift Keying) modulation technology. If 8 time slots are concentrated, the data transmission rate can reach 450 kbit/s. The transmission rate in 3G networks can reach 2 Mbit/s. If HSDPA technology is used, the theoretical downlink rate can reach 14.4 Mbit/s. However, compared with the fixed Internet, there is a huge gap in the transmission rate of the mobile Internet. It is difficult for P2P applications in the fixed Internet to be simply transplanted to the mobile Internet environment.

(3) on the fixed Internet, both parties that can use P2P services are in the network connection status and have independent IP addresses that can be used. In the mobile Internet environment, whether it is dynamic or static IP Address allocation, the Mobile Terminal IP address takes effect only when the PDP (group data protocol) context is activated, in other words, both parties that use P2P applications must complete PDP activation. if the service provider is not in the PDP context activation status, the network side must be able to initiate PDP context activation, launch the PDP context activation process from the network-side device.

The IP address of the terminal will be re-allocated, which will impose some restrictions on the application of P2P technology, and affect the structure of the P2P network to a certain extent, this will have a certain impact on queries and routing mechanisms in P2P networks. In addition, the CPU processing capability and storage space of mobile terminals are not suitable for many successful P2P applications (such as transmission and sharing of large files ), therefore, some optimized P2P services should be carried out on the mobile Internet based on the characteristics of mobile terminals.

Deployment of P2P applications in mobile environments

As the performance of mobile terminals continues to improve, direct application of P2P services on mobile terminals is undoubtedly very attractive. There are two difficulties in deploying P2P applications on mobile terminals. One is the problem of P2P client software on mobile terminals, and the other is the problem of deploying P2P applications in mobile networks.

Currently, mobile phone terminals have many operating systems. Mainstream operating systems include Symbian, Linux, and Windows Mobile. To use P2P applications on mobile terminals, you must develop applications of different versions based on common protocols.ProgramOr client software. This not only requires a unified mobile P2P protocol standard, but also requires mobile terminal manufacturers to open applications on their respective platforms.

due to the processing capability and memory limitations of mobile terminals, in mobile networks, P2P requests cannot be sent in an infinite flooding manner. hybrid architecture is more suitable for mobile Internet. In addition, it is best to limit the application scope of P2P Based on business conditions. For example, P2P services can be applied within the range of communication records of mobile terminals. In this case, a problem occurs. In the communication records, friends are identified by mobile phone numbers instead of IP addresses. in mobile Internet environments, the IP addresses obtained by mobile terminals are dynamically allocated, at the same time, because the mobility of the terminal may change the IP address, a dedicated node is required in the network to query, record, and track the correspondence between the mobile phone number and the IP address.

To implement P2P applications by deploying P2P proxy servers on the mobile Internet, the P2P proxy server provides the following functions: p2P service registration management, initiating PDP context activation on the network side, and maintaining the correspondence between mobile phone numbers and IP addresses. To integrate mobile terminals with P2P services on the fixed Internet, P2P proxy servers can also act as proxies for mobile P2P applications and P2P applications on the fixed network to implement protocol conversion and other functions, it enables seamless integration of P2P services on the fixed Internet and mobile Internet. If you only consider the function implementation, the mobile P2P server can be implemented on the existing ggsn.

It is connected through a 3g wcdma network, and mobile terminals can use mobile P2P services normally.

Mobile P2P business implementation process

Assume that the operator has activated a "Mobile podcast" service. You can use a mobile terminal to take interesting videos and save them on your mobile phone for sharing with friends in your own address book. The following describes how to implement Mobile P2P applications by introducing P2P proxy servers on the mobile Internet through the specific business implementation process.

assume that user a has activated the" Mobile podcast "service, we shared some of our video clips. User A now hopes that friend B in his mobile phone Address Book can enjoy his masterpiece. Therefore, user a sends a request through the P2P software on the mobile phone. After receiving the request from user A, the P2P Proxy Server queries the status of user B on the network. If user B has not Activated PDP, you can initiate PDP activation on the network side, send the IP address obtained by user B to user A, and send user a's request to user B, after receiving a notification from user a requesting to enjoy the personal podcast, user B can view the video shot by user a on his mobile phone.

Assume that multiple users want to enjoy the content in user a's "Mobile podcast", and user a's terminal cannot meet the needs of all users due to the limited processing capability, based on the P2P network management and scheduling mechanism, the mobile P2P proxy server sends requests from these users to users who have accessed the "Mobile podcast" service (such as user B ), it serves as a service provider to satisfy some business requests.

At the same time, user C of the fixed Internet can also use the client software of the PC to input the mobile phone number of a and use the protocol conversion and proxy functions of the mobile P2P proxy server, enjoy the content in A's "Mobile podcast" in the same way to achieve the convergence of P2P services on the fixed Internet and mobile Internet.

Challenges and Solutions

Due to some inherent characteristics of P2P technology, P2P businesses have encountered some obstacles and challenges while developing rapidly in the field of fixed Internet, such as intellectual property protection, network security, unified standards, traffic and billing. Therefore, while deploying P2P applications on a large scale on the mobile Internet, in order to ensure and promote healthy business development, we must face up to these obstacles and challenges and explore targeted solutions.

(1) Protection of Intellectual Property Rights

P2P service ?? P2P applications of shared services all need to carefully examine the copyright issues faced by P2P networks. In terms of copyright protection, DRM (Digital Rights Management) is a feasible method. It can control the distribution, transmission, and use of digital products, so that only authorized users can use digital products within the authorized period. In addition, the real-name mobile phone system that is currently being implemented will also help resolve the copyright issue.

(2) network security issues

The problem of network security is not caused by the introduction of P2P technology, but the equal sharing of P2P technology will make this problem more serious. At present, the emergence of viruses, junk information and hacker attacks on mobile terminals has posed a serious challenge to the network security of the mobile Internet.

There are two solutions to this problem: on the one hand, mobile network operators deploy network security devices in the core network to filter and intercept viruses and junk information; on the other hand, it provides mobile terminals with firewalls and anti-virus software similar to those currently used in PCs. However, these two methods have some limitations. The ideal method is to use the current enterprise-level antivirus software. mobile network operators deploy security and anti-virus servers in a centralized manner and are responsible for timely updates, the mobile terminal downloads and installs the client and updates it on the mobile Internet. Of course, the above process can also be implemented through P2P.

(3) lack of unified standards

At present, a bottleneck of P2P technology development is the lack of unified standards. The difference in interests makes it difficult to form unified standards, which creates artificial barriers for P2P promotion, this is precisely the same as the original intention of P2P freedom and equality.

As mobile P2P is still in its infancy, the unification of standards is relatively easy to solve. With reference to the development model of mobile Dream network, mobile operators can take the lead in the upstream and downstream of the value chain and develop unified mobile P2P technology standards to pave the way for P2P technology applications on the mobile Internet.

(4) Traffic and billing problems

For mobile operators, wireless resources are very valuable. how to strike a balance between P2P services and wireless resource consumption needs to be considered. The specific method is to select P2P services with low business traffic between nodes, and limit the information traffic between these nodes through some methods, such as for P2P-based file sharing systems, do not use a flood-Based P2P service to avoid a large P2P network and strictly limit the size of shared files.

the subscription billing method adopted by the fixed Internet has greatly promoted the development of P2P services. However, mobile Internet is currently billed Based on upstream and downstream traffic, this billing method is almost fatal to P2P businesses, with no one Willing to pay for the upstream traffic generated by others. Therefore, on the basis of content billing, subscription billing for services with certain basic traffic is necessary for the development of mobile P2P services.

P2P technology and applications on the fixed Internet have already achieved great success, but applications on the mobile Internet have not yet begun. Due to the inherent structure and characteristics of the mobile Internet, it is difficult for P2P technology to simply migrate from a fixed Internet to a mobile network. With the continuous evolution of mobile networks and the continuous improvement of mobile terminal performance, the demand for P2P applications in the mobile Internet environment is also becoming increasingly prominent. Based on P2P technology and the characteristics of mobile Internet, this paper analyzes the application of P2P Technology in mobile internet and discusses how to implement P2P applications by deploying P2P proxy servers in mobile networks, at the same time, the challenges and solutions brought about by the introduction of P2P Technology in mobile Internet are discussed from the technical and commercial perspectives.