Innovative features for interference-free IPTV reception
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Internet TV, also known as IPTV, is the third service beyond voice (VoIP) and data services provided to users in triple play applications. About 80% of existing IPTV users access through xDSL, so ADSL2+ is the preferred IPTV operating platform at this stage. Despite the higher bandwidth of VDSL2, ADSL2+ has the obvious advantages of wider coverage and lower cost. It is expected that these two xDSL technologies will continue to be used for IPTV in the next few years and will complement each other. Since xDSL uses conventional copper wire transmission, and the transmission medium of copper wire itself is susceptible to interference, IPTV is sometimes affected. Innovative technologies are now available for interference-free IPTV reception.
For data transmission and services such as video on demand or VoIP, the interference from DSL is usually negligible, but due to the real-time nature of video streaming, DSL interference may cause problems for IPTV applications. Moreover, there is usually not enough time to implement the corrections that are required for the general protection mechanisms of the transport layer (eg TCP/IP). If errors that occur during transmission are not corrected in time, the result is unacceptable image distortion. As shown in FIG. 1, in addition to techniques for improving anti-interference such as interleaver depth or RFI suppression, erasure decoding and gamma layer retransmission techniques can be used to eliminate IPTV image problems.
The erasure decoding technology can improve the impulse noise immunity without changing the DSLAM carrier device. In practical applications, the error protection capability is twice that of the CPE without the erasure decoding function. Therefore, in any actual installation environment, significant improvements can be achieved immediately using the erase decoding technique. Gamma layer retransmission mechanism combined with central office (CO) equipment, intelligent traffic shaping and differentiation algorithm, can optimize real-time services such as IPTV, VoIP or online games, and ensure optimal service by setting minimum delay and maximum error prediction separately. quality. Even with multiple services at the same time, the best quality of service is guaranteed.
Figure 1 The combination of erasure decoding and gamma layer retransmission technology eliminates the problem of IPTV images.
Erase Decoding For the Erase Decoding (ED) function, the receiver monitors the ongoing error correction. It can distinguish the error correction measures used by the RS (Reed-Solomon) decoder and infer the type of interference accordingly. Since subsequent data blocks are likely to be subject to similar interference, the receiver can actively play a role in intelligently adjusting these anomalies by "predicting" the types of packets that may be subject to interference. By erasing decoding, the impulse noise immunity of the CPE can be doubled at most.
However, if the impulse noise lasts longer than a certain threshold, the erase decoding can no longer correct all errors, or image distortion may occur. In order to avoid affecting the market acceptance of IPTV, Internet service providers and network operators cannot allow the provision of services with quality defects, which is also a huge demand for solutions that provide comprehensive error protection. Gamma Layer Retransmission (GLR) provides another interesting approach.
The gamma layer retransmission gamma layer refers to the lowest physical layer that distinguishes IPTV from other services. This layer tells the CPE or CO whether a packet is voice or video. In contrast, the so-called alpha layer retransmission retransmits every lost packet regardless of its service class. However, retransmission solutions can cause additional transmission delays, so it is especially important to ensure that the mechanism is only used for IPTV, without affecting other services such as VoIP that rely on very short runtimes.
The GLR monitors the noise at the transport layer close to the physical hardware, allowing the receiver to react in time and requiring the transmitter to retransmit. If the fast retransmission can be successfully completed, the image can generally be quickly refreshed to avoid image distortion. Of course, to achieve this, the GLR must be supported by both DSLAM and CPE.
From the above information, we may conclude that using ED and GLR at the same time may be the best way to achieve stable and interference-free IPTV. However, this solution is extremely complex. It not only requires a computer with considerable capabilities, but also needs to upgrade the installed base equipment by avoiding excessive workload or excessive cost. .
ADSL gateway single-chip solution with integrated ED and GLR functions At present, the new generation of chipsets such as Infineon's XWAY ARX100 series are equipped with IPTV functions. The professional network manufacturer, the company, has also integrated the IPTV function kit into the DVA-G3170i and DVA. -G306 and other next-generation three-in-one home gateway solutions.
The XWAY ARX168 is an ADSL2+ single-chip product supporting Gigabit Ethernet with dedicated functions required for IPTV and supports wireless data transmission rates above 150Mb/s (WLAN 802.11n). The ARX168 utilizes gamma layer retransmission, erasure decoding, and increased interleaving depth to provide innovative service immunity for media services such as IPTV, providing a better service experience for end users, as shown in Figure 2.
Figure 2 XWAY ARX168 has features specifically for IPTV
Figure 3 XWAY ARX168 structure
The integrated Gigabit Ethernet switch works well with network processors, allowing flexible bridging of different bridging and routing services without undue burden on the application CPU. Two USB 2.0 interfaces provide the convenience of connectivity for all general purpose peripherals. As the media format is digitized, the number and capacity of files that end users need to manage are greatly increased. The integrated Gigabit Ethernet switch and the data transfer rate of over 150Mb/s via WLAN provide the best support for this. As shown in Figure 3, other fast interfaces include: SPI with DMA support, dual UART (including RS-232), and PCI interface.
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