Security Over IP Networks: High Bandwidth Convergence
Integrating your physical security infrastructure with your IP network results in reduced installation and materials costs, simplifies future moves/adds/changes, and streamlines your supply chain. But adding security to your network will also increase bandwidth demand, especially if your video security system uses high-resolution cameras to capture high-quality images.
The focus of this article will be to illustrate what new HD and UHD technologies incorporated into IP surveillance video cameras mean to the network infrastructure. It’s important to understand the benefits gained, the bandwidth needed, and the best way to optimize performance when migrating your analog security system to the IP network.
IP Security Camera Evolution
Up until about 2004, analog–based security cameras were the default choice for many enterprise and data center customers. By 2010, IP-based cameras began to overtake the analog-based designs. The market transition occurred because of several advantages of IP-based systems including:
- Lower cost of ownership
- One cable plant supports both
- Connect, control, converge and power by moving to Everything IP
All of the above-mentioned advantages mentioned are similar to the adoption of VoIP technology. By using the IP network for both voice and data, the user not only eliminates the need for two disparate systems, but they also eliminate the need for two separate support teams. Additionally, like with VoIP, the IP-based video surveillance system can also be powered via Power over Ethernet (PoE) technology. This eliminates the need for a separate dedicated power circuit to support each device – a significant cost savings.
Benefits of IP-Connected Security
IP-connected security presents a number of financial and operational benefits:
Integrated Control. Security over the IP network allows for better integration and control of your video surveillance, access control, and paging systems.
Technology Advancements. IP-based security systems enable technology advancements in compression technologies and resolution to continue to improve system performance.
Cost Benefits. Convergence of disparate systems to one IP network reduces the need for separate installation and support technicians, and allows you to consolidate spending to fewer suppliers to gain greater volume discounts.
Improved Analytics. IP-based security allows for enhanced programming and analytics, such as real-time security alerts and data analysis based on preset user-defined criteria.
Additional Bandwidth Demand on Your Network
However, even with the numerous advantages that IP-based systems offer, there are some new concerns that must be accounted for that weren’t relevant with analog-based systems. One of these is the bandwidth capacity consumed.
As the resolution of cameras continues to increase, more network bandwidth is consumed to support each camera. This also leads to an increase in the available storage capacity required. Both concerns of storage capacity and available network bandwidth can be eliminated with proper planning and investing in the appropriate equipment. But increasing bandwidth also demands more from the network infrastructure.
There are several factors that affect bandwidth requirements from the network:
Resolution: The resolution of IP surveillance cameras varies widely. There are VGA resolutions (600x480 lines of resolution) up to 8.3 Megapixel (MP) cameras which can capture 4k video quality. The higher the resolution, the more bandwidth each camera will require from the network and the greater the stress placed upon the network infrastructure.
Frame Rate: The human eye cannot discern above 24 fps (frames per second) approximately. For reference, Ultra High Definition (UHD) movies are broadcast at 30 fps. Typically, in a video surveillance application, cameras are set to capture anywhere between 8 fps and 20 fps depending on several factors. If the camera will be recording high speed motion, a higher frame count is needed. If the camera will be operating in low light environments, a higher frame count is also needed. The higher the frames per second, the more bandwidth required.
Streaming Mode: There are generally two options with today’s IP surveillance cameras. They are Constant Bit Rate (CBR) and a Variable Bit Rate (VBR). For CBR, this streaming mode streams at a constant rate. This mode is primarily used when monitoring a relatively stable environment, with limited motion and activity. Conversely, VBR is used when monitoring a highly active environment, and the bit rate increases as the activity level increases. This mode requires access to much more bandwidth during periods of high activity than that of a CBR streaming mode.
Compression: Compression is done by a device or software called a CODEC (COder/DECoder or COmpression/
DECompression). In IP video surveillance applications, the CODEC is inside the camera. There are several compression technologies available, and they each have their advantages and disadvantages. Some compression technologies use what’s called a predictive frame approach. This means that if nothing changes from frame to frame, the CODEC only transmits what has changed in order to minimize the bandwidth required. The other main type of CODEC uses a transformative approach. In this approach, the CODEC chops the images into manageable chunks before actually compressing it. Some of the most popular compression technologies include MPEG-1, MPEG-2, MPEG-4, and H.264, with H.264 being the most popular for IP video surveillance applications.
It is beyond the scope of this article to elaborate in detail about each CODEC. However, it is worth noting that the CODEC used can have a big effect on the bandwidth required. Changing the CODEC from MPEG to H.264, for example, can reduce bandwidth requirements more than 50%. Incorporating compression technologies over IP networks can reduce bandwidth requirements, but it also means that each frame is critically important. Frame errors can have devastating consequences for an application like video surveillance, so a robust network infrastructure is very important.
Network Protocols: When transmitting information over IP networks, there is always a balance to be struck between latency and reliability. In applications that are not as time-sensitive, like data transmission for instance, typically employ a protocol like TCP/IP (Transmission Control Protocol). With TCP/IP, if the receiving device determines there are packet errors, it will buffer the data and request a resend from the transmitting device. Upon successful delivery of the resent packets, the receiving device will reconstruct the packet transmission and display the information. Therefore, the TCP/ IP protocol prioritizes reliable delivery over latency. In other applications, like VoIP and video, where there is extreme time sensitivity, then protocols like RTP (Real Time Protocol), or UDP (User Datagram Protocol) are used. When using RTP or UDP, packet errors are simply dropped until error free packets are delivered. The user will notice the dropped packets as the image or audio will be distorted or turn off temporarily until error free packets are received again. RTP and UDP prioritize latency over reliability. The compression technology H.264 for example is usually transmitted with UDP or RTP protocols. Again, a high- quality network infrastructure is critical to video surveillance application and can contribute to minimizing packet errors.
Network Infrastructure Recommendation
An important point to note is that, while Category 6 and 5e are installed today to support IP video surveillance, the probability for success decreases significantly with any of the following:
When multiple cables are bundled and transmitting 1080 HD or especially 4K UHD
- The closer to the maximum length of 100 meters
- Any electromagnetic noise sources close to the structured cabling (fluorescent light ballasts, power cables, etc)
- Operating environments where elevated temperatures occur
When transmitting high definition, ultra high definition or beyond, alien crosstalk (cable-to-cable noise) starts to become a significant factor. The structured cabling system has to be designed to account for alien crosstalk, especially when cables are bundled, and unfortunately Category 6 products were not designed for this.
Additionally, the structured cabling system will most likely also be carrying power (up to 100W) to energize the display monitor eliminating the need for a separate outlet. This will elevate the temperature (especially in a cable bundle), further stressing the network infrastructure. It is critical that you structured cabling infrastructure be specifically designed to effectively minimize both alien crosstalk and heat rise from PoE.