However its use had become widespread with the introduction of cellular phones to common people. The factors siding its use were the convenience of usage, possibility of high range of coverage and high life expectancy. However, the data transmission here was not very reliable, costs more, has lesser speed, can be easily intercepted and not very good quality of service.
Video streaming can be done in different ways. The applications may be Video on Demand (VoD), real-time and near real-time video streaming and Multi Media Systems. The video streams can be multicast or unicast. The data in the video must be first encoded and the choice of encoding depends upon the codec used (i.e. MPEG-2, MPEG-4, H.264, AVI, WMV etc.), the target bit rate, the frame rate, quantization parameter, the resolution and so on. After being encoded the video is transmitted using a streaming server. The clients are expected to reply periodically, depending upon the application, to this server about how much data has been received, whether it has been interpreted correctly, whether there are any errors, whether the bit rate and frame rate is as required and many other details regarding the transmission.
End-to-end delay plays a vital role. ...
Intensive resource requirements are encountered due to the bursty nature of video traffic. If a downlink has been used and the packet size proves to be very large, it leads to saturation ultimately. Moreover if an 802.11b standard has been used in the implementation, it leads to contention problems since every client is expected to have equal opportunity in server access. The quality of the received video can be assessed only by comparing with the original video or through the QoS level parameters promised by the server. This is not so easy to be done in the case of real time transmissions. Also Carrier Sense Multiple Access / Collision Avoidance (CSMA/CA) used in many wireless standards may lead to slow transmissions that suffer numerous time lags. All the above can be taken as the issues to be addressed while using wireless technology in video transmissions.
The wireless standards come under 802.xx category of IEEE standards. The 802.11 standard (for Local Area Networks) specifies the standard for interface between the client and the access point and also for the interface among the clients, in either case air being the medium. This standard is comparable with the 802.3 standard, which is for wired Ethernet LANs. This specification addresses both the physical layer and the MAC layer issues and also the compatibility problems. This entire standard specification makes use of CSMA/CA.
A comparative study of wired network metrics and wireless network metrics based on the QoS is shown below.
WIRED NETWORK METRICS
WIRELESS NETWORK METRICS
IMPACT OF AN UNSTABLE WIRELESS ENVIRONMENT ON MEASUREMENT
Impact of rate adaptation on delay and jitter
Impact of roaming on delay and jitter
Impact of power management on