Streaming to Mobile Devices
After reading Chapters 9 and 10, you should feel comfortable configuring media servers to webcast streaming content to desktop computers over your local network or the Internet. The next step is the deployment of a streaming solution to mobile devices. Before planning to stream content to mobile devices, consider some technical and social facts that will contribute indirectly to your effort. Mobile devices are a direct product of an emerging telecommuting society. Telecommuting is a social phenomenon that evolved when computing changed the nature of the workplace.
Workplaces have drastically changed in the past decade. Before the arrival of personal computers, information was distributed to employees on paper. Business travelers relied on faxes and messenger services to receive materials from their homes or offices. As technology progressed, society has moved away from manufacturing and industrial focus and become information driven. Information technology has decentralized the workplace due to its rapid information transfer.
Social scientists have identified telecommuting as one of the most prevalent and socially dramatic changes that have happened during the information revolution. Personal computers, the Internet, and new exciting mobile solutions promise to provide us with tools to receive, modify, and transfer information over networks in ways never seen before. These are the advantages to using mobile devices. They give us the freedom to access information from anywhere, anytime we want. Mobile devices are small, compact, and easy to operate. We no longer are tied to a bulky desktop computer connected to a network with cables, but have a compact fast solution that we can use as we roam around and that still is connected constantly to the Web.
Mobile devices such as PDAs, SmartPhones, and Internet Appliances have some disadvantages compared with desktop computers or laptop computers connected to the Internet via dial-up networks, such as:
Low bandwidthMobile devices rely on wireless or additional wire (e.g., a PDA connected over a serial or USB connection to a desktop) connectivity. Wireless connectivity has several drawbacks because of the amount of bandwidth that it can deliver and the limitation of existing geographical coverage. In contrast, cellular phones use many networks to maintain connectivity as users travel between coverage areas. The only way to know when coverage areas have changed is to look for the roaming sign on your cellular phone. As long as our cellular phone providers keep us connected (within our calling plan), we do not care about all these technical details. The same should apply to mobile devices using wireless connectivity.
Connection stabilityWired networks provide a more reliable connection than wireless networks. Due to fading, lost radio coverage, or deficient capacity, wireless networks are often inaccessible for periods of time.
Small displayThe size of the screen does not limit the user's experience when a desktop computer is used to access a service. Most desktop PCs arrive with a standard XGA 1024- 3 768-pixel window size. Mobile devices have smaller displays. PDAs have a 320- 3 240-pixel display; SmartPhones use on average a 180- 3 140-pixel size display. This is a small screen that can barely be used for text messaging. Video display and navigation become extremely difficult on such tiny displays.
Limited inputMobile devices do not always have the same input facilities as desktops. These devices use small keyboards and mouseless interfaces. Typing (or key strokes) with a pen assistant (on Palm-size PDAs) is a slower process compared to typing with a keyboard.
Limited memory and CPUMobile devices are usually not equipped with the amount of memory and computational power in the CPU found in desktop computers. The new PocketPC devices are an exception. Using 133- to 206-MHz CPUs and built-in 64 MB of RAM, they provide a new computing experience.
Limited battery powerThe operating time is one of the major concerns for mobile device manufacturers. Battery power restricts operations to approximately four to five hours in most PDAs.
As a result of these issues, mobile devices are positioned as supplementary tools to access information on the Internet or as a way to create and manage personal documents stored locally and waiting to be synchronized with a desktop. Mobile devices become a substitute for desktops when we are on the move, but we still rely on PCs as the primary tool for performing traditional tasks. When we are mobile, we retrieve and display our email, read the news, or draft short messages. The information we create is either transmitted over wireless networks in real time or stored for synchronization (and transmission) after we connect the device to its host computer using cradles (housing devices that help the mobile device communicate with the computer via a serial or USB connection).
If our plan is to stream media to mobile devices, first we must learn how media can be transferred to these devices. Most portable devices connect to desktop computers or to networks to recharge their batteries, to synchronize, or to transfer information. Cellular phones are an exception. All portable devices, therefore, can receive information (or media) when they connect to a network. This can be achieved via a direct connection using a modem (dial-up connection to a VPN), Ethernet card (network connection), or wireless Ethernet card (wireless connection). If we are using a cradle, the USB or serial interface to the desktop PC supports synchronization between the portable device and its host and we must verify that this connection supports the use of the 802.11 protocol. Only 802.11-compatible hardware or software connections support streaming from the network to the mobile device. A network (for this analysis) is the public Internet or a corporate LAN that connects to the Internet. Mobile devices use two types of Ethernet cards and modems, wired and wireless. All Ethernet cards and modems support TCP/IP protocols; this means that they are capable of transferring streaming media data packets.
As described in Chapter 5, telephone companies worldwide are in the process of deploying next-generation or 3G networks that will use higher bandwidth and will eventually be able to stream video. When the technology becomes available, both the consumer and the corporate market will adopt it rapidly. Pilot programs and consumer deployment of 3G networks started in Asia (Japan) and Europe and then reached North America. The future of 3G networks in North America is currently unclear despite the fact that all major wireless providers are slowly deploying CDMA networks that can support 2.5G and the proposed advanced 3G transmissions. Emerging alternatives to 3G networks are the new IEEE 802.15 Personal Area Networks (PANs), IEEE 802.11 Bluetooth technology, and IEEE 802.11b WLANs. All standards apply to enterprise and small-office networks. Table 52 in Chapter 5 lists the most commonly used WLAN protocols.