CHAPTER 6 CONCLUSIONS AND SCOPE FOR FUTURE WORK 6.1 CONTRIBUTIONS AND CONCLUSIONS The performance analysis of the facsimile transmission is highly essential due to the fact that it used for transmitting legal documents, weather charts, picture etc. This research work studied the performance of facsimile transmission in different scenarios using the metric Facsimile Satisfactory Rate (FSR). A detailed analysis of facsimile transmission using the following methods was carried out namely using traditional PSTN network with standard G3 facsimile devices, real-time facsimile transmission using standard G3 facsimile devices and store-and-forward facsimile transmission using standard G3 facsimile devices by analyzing various parameters of image transmission, like image quality, transmission speed, and transmission success rate under varying network traffic conditions. The experiment was conducted during peak hours and off-peak hours of network traffic to study about the image quality under varying traffic conditions. Various characteristics of the packet-based communication such as delay, jitter and packet loss affect the performance of facsimile transmission in an IP network. Although the image quality of facsimile transmission using 108
real-time and store-and-forward methods are comparable to some degree, store-and-forward transmission has better image quality. This was due to the fact that IP network created several timing issues and T.38 lags in providing steady latency which is essential for facsimile transmission. Radio propagation is site specific and can vary considerably depending on the terrain (Pahlavan & Krishnamurthy 2002). Radio waves are affected by reflection, refraction, diffraction, absorption and scattering. Radio propagation is complicated and the signal is usually carried by a multiplicity of indirect paths with various signal strengths. The signal strengths depends on the obstacles they have reflected from or passed through, the distance traveled, the architecture of the environment and the location of objects around the transmitter and receiver. Our study focused on the performance analysis of facsimile transmission using GSM fixed wireless terminal under varying traffic conditions and at varying distances from the base station in rural and urban areas to determine to what extent these parameters affect the image quality of the facsimile transmission. The experiments discussed in this research work gave a clear indication that the facsimile transmission using GSM fixed wireless terminal is dependent on the terrain, the distance of the fixed wireless terminal from the base station and the traffic conditions. The FSR parameter was used for 109
measuring the quality of the facsimile transmission, and it gave detailed information about the image quality under varying parameters. The FSR values indicate the margins of the analyzed GSM network s parameters that can be used as recommendations for the network designers to implement GSM networks through which facsimile service can also be offered. Performance measurements provide authentic data for network planning, monitoring and maintenance. The KPIs (Key Performance Indicator) used in GSM service are paging success rate, TCH (traffic channel) congestion rate, handover success rate, call setup delay etc. All these KPIs are influenced by the traffic volume in the network. Congestion is a daily focus of network optimization and is a key factor affecting the GSM performance (Adegoke, Babalola & Balogun 2008). So, an investigation was carried out under varying traffic conditions to study the effect of congestion on the facsimile transmission using GSM fixed wireless terminal, at varying distances from the base station both in the rural and urban areas. Our research work demonstrated that image quality in the urban areas degraded after a distance of 5 km from the base station. On the other hand, there was no degradation in the image quality of the facsimile in the rural areas even after a distance of 5 km from the base station. This is a clear indication that the facsimile transmission is affected by the terrain and the distance of the fixed wireless terminal from the base station. 110
A comparative analysis involving three different approaches such as integration of fax over IP with SharePoint, S/Fax over IP and Spam Fax Filter for junk fax mitigation, delivers the unique characteristics associated with each approach. S/FAX over IP approach is conclusively better than rest of the approaches, as this approach does not allow the spam fax to get into system. Rather, this approach proposes to use spam filter to accept or discard fax messages subject to verification of integrity and digital signature of incoming fax messages. Also, this approach proposes to assign reasons for rejection of fax messages enabling the senders to receive the status of their messages. 6.2 FUTURE ENHANCEMENTS We plan to work and explore this area more in order to identify best technologies and approaches to prevent spam in fax over IP. We also intend to bring more technologies and approaches under the ambit of comparisons. A detailed research can be initiated on the basis of already covered issues and suitable statistical parameters can be used for rigorous technical comparisons. The future work aims at developing a globally acceptable method to mitigate spam in fax over IP. Wireless networks and mobile communications are developing at a rapid speed. It is clearly evident from the substantial growth in mobile 111
subscribers and terminals, mobile services and applications. 4G is the fourth generation of mobile communication standard and it supports IP packet switching. The major aim of 4G network is to have one Internet core, which can be used for different access networks (Hussain, Hamid & Khattak 2006). 4G provides better spectrum efficiency with optimum service quality. It can also have the best utilization of the channel terminals. It provides better services for multimedia applications. 4G insists that the mobile devices must be IP based. 4G provides greater Internet access speed and also access to high definition video, high quality voice, high data rate wireless channels etc. The features of 4G are given in International Mobile Telecommunication-Advanced (IMT-A) standards produced by ITU. Using this standards, mobile devices can have a data speed of upto 100 Mbps if the device is used when moving and upto 1 Gbps when immobile. 4G is the emerging technology and this service is now available in some countries. Performance evaluation of facsimile transmission using 4G cellular networks is also suggested for future work. Triple play service provides three services over a single broadband connection i.e. two highly bandwidth intensive services such as television and Internet and a less bandwidth consuming service such as telephone. A different form of triple play service namely quadruple play service can 112
support MiFi (My WiFi) phones which can shift from GSM to WiFi. This service has been introduced in some countries. The future work also aims to analyze the performance of facsimile when it is transmitted using the triple play service. 113