In this last part of evaluation for ZigBee Remote Control standard, I would like to compare the new ZigBee technology and the 30+ years old infrared (IR) technology for remote control. Currently, IR technology has been widely applied for remote control. However, it has limitations and difficulties to be deployed for the current and future devices like high definition television. IR remote controls have some interference and field of vision problems. As electronic devices are getting complicated and new trends come to the light, there is no sign of any innovation in IR. As a result, IR technology is becoming a limit on the innovation and that makes it less efficacious whereas Zigbee technology appends highly practical qualities such as longer battery lifetime, two-way communication opportunity, incremented range, robustness against interference, interoperability for multi-vendor products and many more. Now, it is time to scrutinize those qualities in details by comparing with the IR technology.
Firstly, the expected battery life for ZigBee remote controls is much longer than that of IR remote control. At my very early posts, I had explained the battery usage. I will not state that in detail again but consumers have been considered as watching TV for 8.25 hours on average per day and using the menus of the devices 1.8 times per hour. When the functionality of the remote control increments, the number of button presses will increase as well. If ZigBee and IR are examined under these same conditions, it can be concluded that average electric current level that is used is almost the same for both technologies. However, there exists a momentous difference in overall time amount when the average current is consumed. Command transmission takes 1 milisecond (ms) for ZigBee. The transmissions will take smaller than 10 ms if retransmissions are of concern, though single command transmission takes more than 100 ms for IR remote control.
Battery lifetime calculations are given for IR only condition, ZigBee for Set-Top Box and IR for television condition (indicating that older TV is controllable by IR technology), and ZigBee only condition. There are two types of remote controllers for each condition. The types are non digital video recorder (Non-DVR) remote and DVR remote which has more functionality. Battery lifetime in days is also calculated for each remote controller type. Here are the results of battery lifetime calculations for different scenarios:
- In the first scenario, it is assumed that the remote controller is a traditional button-style remote controller:
- In the second scenario, battery lifetime (in days) is calculated for a remote control which has a pointing device such as a touchpad or trackball:
- In the third scenario, the battery lifetime (in days) is computed for a future remote control which will additionally be used to surf on the Net by utilizing the television screen. On average, surfing on the internet is assumed one hour per day via remote control:
It is obvious from the computations that ZigBee technology provides more power efficiency and lower power consumption in total. As the functionality of the remote control increases, the battery lifetime of it will decrement significantly. In the last scenario, the battery lifetime of ZigBee remotes drop till one and a half time of IR remotes’ battery lifetime. To sum up, ZigBee remote control has better performance than IR remote control and this better performance will enhance the user pleasure, will be more environment-friendly since the battery usage will decrement and call center traffic will be reduced.
Secondly, ZigBee technology removes the line of sight restriction, enlarges the range of remote control and supports two-way communication. IR remote controls are directional and need to have a direct path towards the target device. Using two transmission diodes to widen the beam or incrementing the power to benefit from the reflections could be solutions for IR but the performance of the remote control will rapidly drop due to fast reducing battery power. In contrast, ZigBee remote controls have omnidirectional radiation pattern. Therefore, having obstacles between the controller and target devices is not a problem. The wavelength is also appropriate to penetrate through furniture and even reach another room.
IR remote controls directly utilize the battery power to transmit beam from IR-emitting diode. Since the battery power is directly used, the voltage gathered decrements in time. This has some significant drawbacks. The range of remote control shrinks, remote control starts to get affected by the furniture and it needs directing carefully towards the target device. Moreover, it may be necessary to press the buttons more than once in order to send a command. ZigBee changes all of those. It has larger range, you may even use from another room. It does not directly use the battery power but it takes the power after a regulator. Thence, the voltage level does not change in time until a threshold level of a battery, which is about to be drained, is reached. In addition, it is enough to press a button one time because ZigBee device tries to reliably send the command until it gets an acknowledgement. After mentioning acknowledgements, it would be better to express that ZigBee has bidirectional communication feature which IR technology does not have for remote controls. Due to two-way communication, ZigBee remote controls can be programmed, fixed or upgraded via the network by receiving firmware.
Thirdly, ZigBee remote controls are robust against interference in the environment. TV backlighting is a troubling issue for IR remote controls and it creates interference because the modulation rates are the same for backlighting and IR signal. ZigBee is not only immune to backlighting interference but also immune to any RF interferers.
It will take too long to examine all advantages of ZigBee in detail. So, I will continue with other advantages in a short form. IR remote controls are special for the device that they command. In contrast, ZigBee remote controls work with Set-Top Boxes, televisions, audio/video recorders, sound systems and some more electronic devices. Clients can manage all those devices from a single remote control. ZigBee engenders practicality and interoperability as IR remote controls changes with respect to the device type and also the brand. Furthermore, IR technology is a burden on the electronic device manufacturers because they had to enhance or license expensive universal IR command databases. ZigBee remote controls include improved user interface and faster command transmission (1 ms for ZigBee, more than 100ms for IR).
Finally, security is an important issue for the devices which are utilizing a network. Cryptographic mechanism of RF4CE specification protects the commands sent. Transmitter sends receiver-specific command and receiver understands whether the source is trusted or not. Replication of the commands is also avoided in order not to get command flood from an attacker device or attacker devices which may create denial of service. As I pointed out before, the remote control can be upgraded or fixed via network. Security has a significant importance for such situation. Someone may try to change the features of a remote control without the permission of the owner. Moreover, one might even try to take control of the electronic devices in an environment. ZigBee avoids those unpleasant situations with its 128 bit cryptographic keys, applying AES-128 security scheme.
