5.2 Implementation Issues

5.2  Implementation Issues

            There are some implementation issues that limiting the design and operation of the offline email system as per below:

i)                    The offline email system accessibility is limited by the wireless local area network (WLAN) coverage range. The D-Link DWL-2100AP was used as a Wi-Fi access point at the offline mail server. Table 5.1 shows the effective range of D-Link DWL-2100AP. Details of D-Link DWL-2100AP shown in Appendix C. Riger DB 108-WL Wireless ADSL Modem 2/2+was used as a Wireless ADSL Modem at the online mail server with the same effective range of D-Link DWL-2100AP as shown in Table 5.1.

Indoors		Outdoors
Transfer Rate	Effective Range	Transfer Rate	Effective Range
54 Mbps	30 Meters	54 Mbps	95 Meters
48 Mbps	32 Meters	11 Mbps	290 Meters
36 Mbps	37 Meters	6 Mbps	420 Meters
24 Mbps	45 Meters
18 Mbps	60 Meters
12 Mbps	68 Meters
9 Mbps	77 Meters
6 Mbps	90 Meters

Table 5.1: D-Link DWL-2100AP indoors and outdoors coverage range

           

ii)                  The speed of database synchronization process limited by the network data transfer rate of the Wi-Fi access point at each server computers. The D-Link DWL-2100AP used as a Wi-Fi access point at the offline mail server has network data transfer rate up to 54 Mbps which is 54 megabits per second for Standards IEEE 802.11b/g. Riger DB 108-WL Wireless ADSL Modem 2/2+was used as a Wireless ADSL Modem at the online mail server. The network data transfer rate is up to 54 Mbps for Standards IEEE 802.11b/g. It is the same as shown in Table 5.1 for D-Link DWL-2100AP. The ADSL, ADSL2 and ADSL2+ network data transfer rate are up to 24 Mbps.

iii)                Infomediary device battery life is important to ensure the data can be moved from both offline and online side without interruption. LG Optimus 3D (P920) can offer up to 250 hours in standby mode as shown in Appendix D.

iv)                User only can register a new email account at online mail server side. This offline email system did not enable email registration page on the offline mail server because of conflict may occur with online mail server registration database or several other offline mail server registration databases. Since an offline mail server can be more than one and only one online mail server required, registration system only implemented on online mail server to avoid database conflict. Data conflict most likely happen when same username registered on several mail servers. This will cause database synchronization cannot be done when either data might be deleted or both.