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Beat bottlenecks in WLANs and retain legacy copper infrastructure

Beat bottlenecks in WLANs and retain legacy copper infrastructure

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By eeNews Europe



In most cases, that infrastructure is dominated by 1-Gigabit per second copper cables that transport access point signals back to Ethernet switches. But connectivity demands and next-wave technology standards require greater bandwidth than 1Gbps.

Increasing the ability of the existing infrastructure to accommodate higher transmission rates promises to alleviate this infrastructure bottleneck and accommodate the growth in enterprise wireless connectivity in the most cost-effective, least disruptive way.

Enterprise local-area-network (LAN) technology deployed in most offices and campuses around the world has remained static at 1-Gbps transmission speeds for more than a decade. The broad proliferation of mobile devices generating traffic through these networks demands capacity well beyond this rate.

Figure 1. Copper cables in the walls and drop ceilings of enterprise campus buildings represent the current status quo of access network infrastructure and support 1-Gigabit per second data rates.

However, a variety of next wave technologies, such as 802.11ac access points, demand greater bandwidth.

802.11ac Wi-Fi access points (APs), and Wave 2 in particular, demand Ethernet backhaul bandwidth of up to 6.9 Gbps on the wired infrastructure side, but the copper cables that connect these WiFi APs to enterprise switches have reached their design limits. The vast majority of these UTP cable connections are either Category 5e or Category 6. Replacing these cables with higher speed 10Gbps links of Category 6a or above is costly, labour intensive, disruptive, and requires a monumental effort to upgrade billions of installed connections. Upgrading to fibre optic connections would be even more expensive and intrusive. Theoretically, enterprise and campus network administrators might upgrade these connections to 10 Gbps or higher as soon as possible. In reality, the prevailing attitude is to leave the legacy cable infrastructure in place for as long as possible because it is still functional and reliable and the cost of replacing it is prohibitive.


By employing unique mixed mode signal processing in the physical layer ICs of these network connections, support for speeds up to 2.5 Gbps and 5 Gbps can be established on the majority of existing cables deployed today in the enterprise. This upgrade will enable both 802.11ac WiFi APs and enterprise switches to meet the demand for greater capacity and higher volumes of traffic in enterprise access networks, allowing service providers to deliver a higher quality of experience to users of mobile devices.

Upgrading the Enterprise

The migration to faster wireless access network speeds is essential to help enterprise keep pace with growth in smart phones, tablets, bring your own device (BYOD) access, Internet-of-things (IoT), improved quality of service, 4k HD video, security, surveillance, teleconferencing, and simultaneous support of multiple users (MU-MIMO). Adoption of these technologies and trends requires a corresponding upgrade of the wired network infrastructure.

Adoption of advanced wireless connectivity technologies, such as 802.11ac WiFi and small cells, increases network access speeds to more than 1 Gbps. New WiFi/WLAN access points are being deployed in high volumes to replace slower 802.11n technology and the first wave of 802.11ac technology. Second generation 802.11ac, in particular, provides nearly 20 times the bandwidth compared to 802.11n, aggregating total payload throughput of up to 5 Gbps.

The wired network side of 802.11 access points attach to the central enterprise switch through 1-Gbps Ethernet copper cables, which are predominantly unshielded twisted pair Cat5e or Cat6. They were designed to transmit these speeds on cables up to 100m in length. These cables are so successful that they comprise more than 90% of all wired enterprise connections running through walls and risers of campuses today, and they represent billions of installed ports around the world. In fact, even though higher speed cables and technology have been available for a few years, these cables continue to be deployed in high volume, even now representing 70% of new installations, according to some surveys. Therefore, they are not going away anytime soon.

Figure 2. Approximately 90% of copper cables installed in the walls and risers of enterprise campus networks around the world support only 1 Gbps. Next-wave wireless network technology requires greater bandwidth but many network administrators are disinclined to replace legacy cables because of cost and disruption.


Upgrading the wired infrastructure requires replacing existing copper cables with higher speed copper or fiber-optic ones. The cost of upgrading each cable can be conservatively estimated at $300 per cable pull. Therefore, a campus-wide upgrade could cost hundreds of thousands of dollars or more. Wholescale replacement requires substantial installation costs, time, and invasive disruption to the physical infrastructure of any enterprise building. Cost estimates are billions of dollars worldwide.

Through advanced physical layer (PHY) integrated circuit (IC) technology, legacy enterprise networks can upgrade to meet rapid growth of mobile device connectivity and accelerate adoption of 802.11ac at a fraction of the cost of replacing the entire cable infrastructure.

PHY ICs [with uprated specifications] can be deployed in next-generation wireless access points and network switch interfaces, allowing administrators to avoid the wholesale replacement of cables as well as the associated installation time and physical disruption.

Proven high-speed signal conditioning can be employed in the ICs to boost the speed well beyond the designed limits of 1 Gbps for twisted pair copper cabling up to 100m in length. A new silicon architecture can be devised to increase Cat5e and Cat6 line rates up 2.5 Gbps to 5 Gbps.

The approach can exploit a mixed-mode signal processing architecture commonly used in 10GBASE-T technology. Auto-negotiation allows the silicon to accurately select speeds ranging from 100 Megabit Ethernet (100ME) to 1 Gigabit Ethernet (GE), 2.5 Gigabit Ethernet (2.5GE) and 5 Gigabit Ethernet (5GE). The silicon can also switch to the IEEE standard 10GBASE-T mode, given sufficient bandwidth found in data centre-class Cat 6A cables.

Addressing the technical barriers is non-trivial. However, once it is possible, an effort to support interoperability through an array of complementary silicon vendors, board manufacturers, reference design makers and original equipment manufacturers should help this technology become widely acceptable anywhere multi-vendor networks are deployed. Once a consortium is formed and a consensus is reached on the technical specifications of this technology, efforts can be launched to make this an industry standard. One effort that embodies this approach is spearheaded by the NBASE-T Alliance.

So, while enterprise networks around the world are swamped for demand by growing numbers of mobile devices, efforts to upgrade these networks are taking place on a wide scale. The area that has been overlooked the most, however, consists of the copper cable connections that reside within the walls and risers of most large office buildings. As network administrators are averse to upgrading this cable, upgrading to the connections to support 2.5 Gbps and 5 Gbps rates can greatly enhance wireless connectivity and help network administrators accommodate exploding demand from the growth of wireless devices.

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