Where We Are and Where We’re Going
The TEK Center at Berk-Tek in Pennsylvania recently published research on the future of wireless technology. Read some of the findings below.
As wireless devices become more and more prevalent worldwide, data consumption has also been increasing significantly. With this, industry standards entities are making efforts to enable faster data transmission. Developments in BASE_T, combined with Power over Ethernet, will add further stresses to the copper infrastructure that supports wireless access points. Deploying 6A or higher components will continue to yield future dividends through lessened disruptions and increased flexibility for the next generation of wireless deployments.
Rapid Growth Leads to Rapid Advancement
Because of the accelerating growth of wireless consumption, the expectations and stresses upon WiFi infrastructure will grow exponentially. Cisco’s projections for the next 5 years are that the average smartphone will create a nearly five-fold increase in overall network traffic. This growth will be driven by video consumption. The expectations placed on WiFi deployments are also increasing currently. Providing the adequate bandwidth for data-intensive applications, ensuring a strong signal to maximize speeds, and servicing a continually increasing number of devices are now the major factors driving speed and capacity upgrades to ensure clients are served in an acceptable fashion.
IEEE 802.11ac Drives Base-T Expansion
Client device densities that were considered extraordinary prior to 2014 are now more typical of today’s average wireless-enabled situation. To address rising demand, IEEE 802.11ac was created to increase the bandwidth available to each wireless device. The first deployments of 802.11ac continued to be satisfied by a 1000BASE-T drop, as the maximum aggregate capacity of the access points was approximately 850Mbps. However, later generations have seen that number increase above 1GBps, with the expectation that eight antennae WAPs could reach an eventual maximum of 6.9Gbps. This increasing aggregation of throughput is powering the need for copper backhaul capacity greater than 1Gbps, which the IEEE 802.3, owner of the BASE-T technology, is quickly addressing. However, there are added technical developments underway that will place further weights upon the infrastructure.
Next Generation to Push More Through Air and Copper
Anticipating the constant growth of the wireless market, IEEE 802.11ax is in development with the anticipation of providing improved speed, flexibility and capabilities to wireless networks. There are several goals articulated by the task force working on these developments but targeting a 4X improvement over 802.11ac in average throughput is high on the priority list. This will be attained by improving spectral efficiencies. Rather than using new frequencies, the task force will improve the encoding and deliver more bits per Hertz.
Increasing throughput to a client could be achieved through increased received signal power. However, due to the broadcast signal power limits placed upon the equipment, increasing signal strength to a client is not as simple as “turning up the volume” and will likely necessitate higher densities of access points.
2.5 and 5GBase-T: The Impact of Alien Crosstalk
The drastic increase of wireless bandwidth consumption has driven backhaul speeds at the access point beyond 1Gbps. Today, a solution comprising 10GBASE-T silicon with 400MHz capacity and Power over Ethernet (PoE) to power the access point would be too expensive for speedy market deployment. One conceivable way to address this issue would be to deploy multiple 1000GBASE-T cables. However, this would require the access point and switch to include one RJ-45 port for each gigabit of capacity. At 5 Gbps or more of throughput, it quickly becomes clear that a single RJ-45 solution is more compact and easier to manage than multiple ports.
A more plausible and pleasant market solution is to deploy a short-term step that reuses existing 10GBASE-T encoding to enable a single jack solution while using simpler and more cost-effective PoE magnetics. 2.5GBASE-T and 5GBASE-T provide this method to increase backhaul capacity, but deployment of these new interim speeds may not be as simple as anticipated.
There is a strong desire among the standards bodies to make 2.5GBASE-T and 5GBASE-T capable of operating over existing cabling. However, alien crosstalk is proving to be a limiting factor in Category 5e and Category 6 channel reach, as it was never specified for these categories. TIA is merging its copper cabling infrastructure expertise with technical modeling guidance from IEEE to develop TSB-5021: Guidelines for the Use of Installed Cabling to Support 2.5GBASE-T and 5GBASE-T with guidelines for testing pre-existing cabling to predict 2.5GBASE-T and 5GBASE-T system performance. The TSB provides equations to allow field testers to qualify channel performance with respect to system expectations. The objective of the TIA work is to determine the boundaries by which most installations will operate. However, there is no guarantee that all Category 5e and 6 materials will provide the expected performance. It is also significant to note that the TSB can only offer recommendations at this point, since no additional requirements can be added to standards that have already been finalized.
The TEK Center at Berk-Tek has completed system testing on various levels of Category cabling to understand the impact of alien crosstalk on cable and system performances in conjunction with bundling. The test results provide clear indications that alien crosstalk plays a significant role in limiting system reach with cabling not designed for alien crosstalk mitigation (Category 6 and 5e). While two different designs of a Category 6+ cabling exhibited significantly different capabilities with 2.5GBASE-T, the results were substantially closer when operating as 5GBASE-T, due to the increased susceptibility of data corruption to alien crosstalk at higher speeds. It is possible that the reach of Category 5e and Category 6+ channels could be extended through unbundling. However, the physical isolation of a channel from its neighbors is not always practical and may yield only enough improvement to reach a limited number of additional devices or access points.
The alien crosstalk performance and extended reach margin of Category 6A make it the best solution for wireless deployment. Unlike Category 6 and Category 5e, whose alien crosstalk performance has not been specified, Category 6A offers ample margins to assure 100m system operation and data integrity regardless of network speed or proximity of adjacent channels.
Power over Ethernet and Heat Rise
Power over Ethernet (PoE) is a convenient method to power remote devices, such as WAPs, through communications cabling. As devices become more sophisticated and applications more complex, power consumption increases.
The IEEE 802.3bt group is specifying equipment to supply a maximum of 100W (1 amp per pair). This increased power deployment will result in increased heat generation within the cabling infrastructure. The TEK center performed a study to characterize heat rise within a bundle as 1amp was applied to each pair within a cable, representing the highest expected PoE deployment. Berk-Tek’s Category 6A LANmark-XTP solution with a unique intermittent shield yielded a distinct advantage over Category 6 and Category 5e, allowing for bigger bundles with less heat gain.
The TEK Center then extended the heat studies to understand the impact to 2.5BASE-T and 5GBASE-T four-connector channels as they service devices such as WAPs. Testing revealed that the Category 5e and Category 6+ channels lost 4-5m of reach at 75°C when compared to their ambient 20°C state. The Category 6A channels also exhibited a proportional reduction in system reach; however, due to the excess margin inherent to the design, the system would continue to operate at 100m. This reduction in length is important as most infrastructure validation is performed when the network is off and not operating under the worst-case conditions.
Mitigation performed according to TSB-5021 may not be sufficient as it does not take temperature into account when calculating system margins. When the deployed system is operational and drawing power, an increase in the bundle temperature due to ambient temperature rise and/or cable heat generation may cause mitigated Category 5e and Category 6 channels to fail. The result is the end user will have to further mitigate the channel causing additional down time and site disruption. The use of Category 6A cabling will avoid this issue and provide enough margin to withstand the increased temperatures, delivering data under the duress of increased speeds, alien crosstalk, and elevated temperatures.
Cable and Infrastructure Recommendations
The continued growth of wireless data consumption has pushed the industry to develop additional methods of increasing capacity. While it is possible that these new technologies may work on existing infrastructures, it is clear that modifications to existing Category 5e or Category 6 wireless infrastructure may be required either in the form of mitigation to improve electrical performance or increased number of drops to increase capacity. The superior network capacity, alien crosstalk performance, resistance to heat generation from PoE, and extended reach margin of Category 6A cabling, make it the best choice for wireless deployments.
The Case for Zone Cabling
TIA published TSB-162-A: Telecommunications Cabling Guidelines for Wireless Access Points in November of 2013, to provide directions for cabling in anticipation of growing wireless deployments. IEEE 802.11ac was given specific consideration by selecting a cell size of 3,600 sq. ft. and suggesting a centralized drop configuration. However, Berk-Tek has always recommended two Category 6A drops so additional WAP density could be added with minimal disturbance.
It is anticipated that future wireless technology deployments may need a higher density of WAPs, so zone cabling with Category 6A cabling should also be considered as a design option. Zone cabling is the concept of dropping multiple cables to a centralized location in order to provide additional capacity, which can be used in the form of:
- WAP Aggregation: Multiple cable drops are utilized for a single WAP.
- Increased PoE: In the case of large WAPs, power delivery can be made more efficient through the use of more copper pairs.
- Higher WAP density: Deployment of more WAPs within the cell to reduce the coverage area per WAP.
While some of these new wireless use cases and applications are anticipated to work within today’s 802.11ac WAP density, many applications that utilize positioning functions will benefit from an increased WAP density. Deploying a robust zone cabling infrastructure today using Category 6A or higher components, such as Berk-Tek’s LANmark-XTP, will continue to yield future dividends through minimized disruptions and increased flexibility for the deployment of the next generation of access points.
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