As video surveillance increasingly adopts IP-based technology, more advanced functions and features are needed in data transmission. Transmission devices such as PoE switches are being built as the backbone for IP-based surveillance. A&S takes a look at its latest technology developments and future trends.
As video surveillance increasingly adopts IP-based technology, more advanced functions and features are needed in data transmission. Transmission devices such as PoE switches are being built as the backbone for IP-based surveillance. A&S takes a look at its latest technology developments and future trends.
The use of PoE switches in surveillance infrastructure provides a cost-effective solution. Video and power can be streamed on the same Cat-5 cable, making system inspection and maintenance easy.
PoE switch applications range from correctional facilities, substations, railways, airports, maritime installations, factories, building automation projects to intelligent transportation systems.
An Infonetics report found the worldwide Ethernet switch market dropped 26 percent in the first quarter of 2009. All switch port shipments were down during this period, but demand still grew for 1-Gigabit PoE switches, 10-Gigabit layer 3 fixed managed switches and 10-Gigabit chassis switches. With improved technology and a recovering market in 2010, switch providers are expecting more growth.
In general, there are no specific rules or regulations governing system designs. However, there are mandated specifications for systems in different verticals. "Manufacturers with extensive industry experience should understand each industry's know-how and acquire the necessary certifications and approvals," said Joe Lai, Field Applications Engineer, EtherWan Systems.
Technology
The number of PoE ports per switch range from six, eight, 10, 12, 24 to 28 ports. "An example of port combination for an industrial-grade switch is 24 100-Mbps ports with four 1000-Mbps ports," Lai said.
Customized solutions can offer a mixture of copper, PoE, fiber-optic and Gigabit ports in one switch. As many as 12 small form factor pluggable (SFP) fiber ports can be included in one switch. "Switches with fiber-optic ports are often used in large industrial deployments where the network is large," said Stephen Tseng, Manager, Ethernet Switch Product Department, D-Link.
For back-end data transmission, many switches have one to three Gigabit ports. The amount of data transferred back ranges from 1-Gigabit to 10-, 100- or even 1,000-Gigabit, said Darren Chen, Product Manager, Moxa.
Megapixel network cameras require more bandwidth to stream larger images. "Switches with a combination of fiber-optic and Gigabit ports are common for large-scale multisite surveillance applications," said Andy Leung, Senior Product Manager, APAC, Juniper Networks.
If required, PoE switches can provide power over existing Ethernet, twisted-pair and hard-wire cables. "We have switches that come with removable modules, so users can easily change the features according to their needs," Lai said.
Distance
On average, the longest transmission distance for both PoE and Ethernet switches is 100 meters. "For the SFP transceiver module, its 1000-BaseEZX and LC Connector can transmit at distances of up to 110 kilometers," said Chen.
Fiber-optic transmission ports can send signals as far as 120 kilometers away. "The distance may increase, if fiber optic manufacturers develop transceiver modules that surpass current distances available," Lai said.
Data can be transmitted over hard -wired cable with PLC equipment. "The
Theoretical transmission distance is 300 meters, but the practical distance is 100 meters," Tseng said. "We plan to offer media converters that can offer PoE functionality across coaxial cable."
Power
PoE switches provide flexible and reliable power for devices. Most industrial-grade PoE switches comply with IEEE802.3af standards, supplying a maximum of 15.4 watts (W) per port.
However, power-hungry devices are frequently connected to switches, such as PTZ network cameras, wireless access bridges, routers and network video phones with large displays. With an increase in high-power devices, more commercial-grade PoE switches are adapting the IEEE802.3at standard, delivering double the power at 30W per port.
With management settings, the switch can supply either 25.5 W or 30 W through an 802.3af port. "PoE plus is becoming a trend in commercialgrade switches," Chen said. "This development allows for easier network configuration and reduces system maintenance and operation costs."
"We also have PoE splitter which separates power and data from a PoE input and can distribute 24 V DC power to non-PoE devices," Chen said. Some switches can boost available electricity to power more devices.
Management Functions
Transmission devices are featuring more intelligence, making them smart edge devices. Network reliability is key. Other than traditional MSTP, RSTP and STP network redundancy mechanisms, advanced turbo ring and chain structures can shorten recovery time to as little as 5 milliseconds.
Powered device (PD) failure recovery is possible with managed PoE switches. "Users can reset the PD by powering it on or off to bring back its default status," 
Chen said. "It also offers different power options during day and night or by schedule."
Intelligent functions built into switches ensure transmission stability. Switches with multicast support reduce network traffic by duplicating video streams and transferring them to different servers, Tseng said.
Network performance and video transmission are also ensured by the quality of service (QoS) function, which assigns priority for video streams to avoid network jittering, said Armine Beybutyan, Product Sales and Marketing Manager, Korenix Technology.
With bandwidth management, users can control each port's rate of I/O data streams. "Simple network management protocol also allows switches to report events to the management software," Lai said. "Port authentication, power utilization and remote status monitoring are made possible."
Prioritizing data transmission optimizes system performance. "PoE switches allow multicast interface, allowing both surveillance data and multimedia streaming through the same device," Leung said. "With limited bandwidth, prioritizing traffic ensures better real-time streaming."
Data Protection
As IP-based technology is more widely adopted, data protection is an important issue for transmission.
PoE switches include data security features that can lock a network camera's IP address. By securing the camera's IP address, it prevents malicious denial-of-
service (DoS) or distributed-denial-of-service (DDoS) attacks and detects viruses. This feature protects video data privacy," said Angus Shih, CEO, ORing Industrial Networking. "Our system also automatically prevents DoS/DDoS intrusion within a shared network, and it locks the source IP address to protect network cameras and NVRs from attacks."
Apart from data intrusion detection, management can also be done through system settings. "Switches can be configured to authenticate the camera by using its IP address or 802.1X authentication protocol," Tseng said. "Only valid cameras can be allowed to connect to the network."
Routers with firewalls and gateways grant a higher level of protection. "A secured firewall and VPN router often have basic functions such as NAT firewall protection, which further ensures data security," Chen said.
Selection Criteria
Selecting systems from reputable companies ensures a worthwhile investment. Many quality companies offer three- to five-year warranties on their solutions.
Network solutions must comply with application-specific specifications, which are 
highly customized depending on usage. "Specifications must accurately conform to the industrial standards,” said Lai. "A one-stop shop where users can find total solutions is ideal.”
Stability must also be ensured with ruggedized devices that operate under harsh environments, which may have to be of ATEX explosionproof grade. Switches that have IP67 and IP68 grade protection with fanless designs are more reliable. "Uniquely made M12 connectors with reliable mechanical designs provide solid Ethernet and PoE connections for various applications, such as railways," Chen said.
Cost-effective products should use energy efficiently. "Our engineers have designed the PoE booster technology, which allows PoE switches to accept 12 to 24 V and release 48 V power, making the switches suitable for vehicle and transit surveillance applications,” Beybutyan said.
Scalability is preferred. "Even for large industrial use of switches, users don't need 
to purchase a large switch on day one," Leung said. "We offer scalable solutions, so users can add more PoE ports as time goes by."
Challenges and Outlook
While managed PoE switch technology advances, it still has challenges to overcome. For example, wireless transmission of real-time video images is slow. "One of the toughest challenges we recently encountered was transmitting a network camera's real-time video wirelessly via our wireless AP," Lai said. "To ensure a consistent signal and image quality over long distances in a wireless environment, we had to adjust the camera's quality settings — resolution, FPS and codec — to be reasonable. That means it could not exceed the maximum bandwidth throughput for our wireless AP. It is essential to determine the best frequency, number of available channels and amount of wireless interference."
In terms of hardware development, cooling for fanless switches is tricky. "To improve this, R&D personally must carefully design the PCB layout for better heat dissipation to increase device efficiency," Chen said.
With more IP video surveillance equipment such as megapixel cameras, reliable networks with faster data transmission speeds are crucial. In the future, 
manufacturers are developing more 24-Gigabit ports per switch for data streaming. Data transmission distance is expected to reach 200 kilometers.
Multigateway and different streaming media such as wireless, fiber optics and Gigabit PoE will be developed. "We expect 10-Gigabit transmission to be used increasingly as prices fall," Shih said. "Switch functions will become more powerful with user-friendly GUIs."
More makers are improving system manageability. "D-Link is developing camera recognition technology on switches," Tseng said. "Once a camera is detected, the switch automatically assigns an appropriate QoS to stream videos. Multicast settings will also be applied automatically."
Green products are another transmission trend, for lower power consumption. "We choose hardware components with materials that are RoHS compliant and environment-friendly," Lai said.