4G Wireless Video Communications

11

Interactive Video Communications

11.1 Video Conferencing and Telephony

Video conferencing and telephony are typical examples of interactive video communications, as nowadays mobile phones and portable devices are very popular. The major difference between video conference and telephony with other multimedia applications, such as multimedia messaging (MMS) and multimedia streaming is that the video conferencing is delay sensitive while others are not.

In the past decade, point-to-point protocols (PPP) have been in common use for TCP/IP communications (the protocol used by the Internet) over a telephone line. Using the Internet, multimedia communication can be achieved without incurring any long distance charges. On the other hand, the usage of a cable modem along with DSL technology has enabled broadband Internet access, where the cable modem is used to deliver broadband Internet access taking advantage of the unused bandwidth of the cable television network. The bandwidth of the cable connection varies from 3 Mbits/s to 30 Mbits/s and the upstream speed ranges from 384 Kbits/s to 6 Mbits/s. The DSL modem, on the other hand, takes advantage of the unused frequencies in the telephone line and varies in speed from hundreds of kbits/s to few Mbits/s. With the development of the 3G and 4G, the constraint on bandwidth for a wireless system to carry video content has been lifted, in addition, more sophisticated access protocols such as HSPA, EDGE, etc. hit the market and give a strong ...