WiFi's Best Kept Secret

Wi-Fi’s Best Kept SecretWhite PaperCo-channel Interference Test Report

Overcoming the Ultimate Wi-Fi ChallengeCo-channel interference is a problem common to any large-IEEE802.11 and all other wireless networking technology,scale wireless deployment. However, no wireless vendoraccessing wider bandwidth offers an effective means ofhas tested what would happen when operating two accessachieving higher transfer rates. For example, a single streampoints set to identical channels. The reason for this is that,at the 802.11ac standard supports 433 Mbps at 80 MHzuntil recently, there existed no effective solution tobandwidth and up to 866 Mbps at 160 MHz. Spectrummanage or eliminate co-channel interference.frequencies allocate just six and two non-overlappingchannels for 80 and 160 MHz channel bandwidths,From the earliest stages in the development of smart-respectively. The situation is further complicated by theantenna technology, ZyXEL’s primary goal was to resolvefact that not all six channels are available in every region.the issue of co-channel interference.In addition, experienced IT staffers know to avoid usingcertain channels within the range of weather radar, whichWe all love high-quality video streaming and lag-free mobilecan negatively impact wireless signals operating on thelearning made possible by today’s 802.11ac APs, butsame frequency.the advantages of this new technology come at a price. *1121081041006460565248444036UNII-3WeatherRadarDFS ChannelsWiFi ChannelChannel WidthUNII-2-Extended124UNII-1FCC Domain20 MHz40 MHz80 MHz160 MHzFrequency 51705250533054905710573558155835 (MHz)How bad can the effects co-channelinterference be?larger than the -82 dBm line. A client is able to establish aReducing transmission power may seem to be the obvious-90 dBM, depending on the AP and the client’s capability. Assolution to alleviate the impact of co-channel interference,long as the client is within the coverage area of the other APbut this remedy comes with its side effects — reducedusing the same channel, co-channel interference can occur.coverage and an increase in the number of dead zones. InThis can result not only in a client failing to receive a packet,addition, co-channel interference raises several complexbut can also cause a massive delays as both APs continue toquestions: Can APs effectively send data in the presence ofreattempt failed transmissions, significantly reducing dataco-channel interference from other APs, and if so, can thetransmission rates.connection with an AP when the AP signal is as low as -80 toclient receive the data and send it back?In this benchmark test, two APs are set up in line with aIn accordance with the 802.11ac standard, an access pointreceived signal below -82 dBM. This ensures that both APswill cease transmitting when it receives a signal stronger thanare able to transmit continuously while interfering with-82 dBM — what is known as the clear channel assessment.each other’s signal as multiple clients link to them.In practice, when the signal between two APs falls to-82 dBm — and the mean distance between the two APsThe following test results show that ZyXEL Smart Antennais between 300 to 400 meters in an open space or blockedtechnology offers a breakthrough by providing widerby 2-3 brick or concrete walls — co-channel interferencecoverage and delivering the best throughput while exposedcan be expected. In addition, the impacted area is muchto co-channel interference. ZyXEL placed number-one in2

the coverage test by delivering the best throughput to theWi-Fi performance as much as 100% when compared tomost locations at both 2.4 GHz and 5 GHz, as well as 66%products from other industry-leading competitors.higher throughput in those locations that were difficultto reach. In the co-channel interference test, the SmartWhat follows are the findings of our Co-channel InterferenceAntenna advantage of the ZyXEL APs improves overallChallenge.Devices Under TestVendorModel namePHYSpatial streamsRadioSmart antennaArubaAP-225802.11ac3x3:3Dual radio-Cisco2702i802.11ac3x4:3Dual radio-RuckusR700802.11ac3x3:3Dual radioYesZyXELWAC6503D-S802.11ac3x3:3Dual radioYesKey Finding ZyXEL APs featuring Smart Antenna achieved the best coverage.In the coverage test, the Smart Antenna-equipped AP from ZyXEL achieve the best results at both 2.4 GHz and 5 GHz,and delivered 66% better throughput in difficult-to-reach locations. Reconfigurable antenna technologies are the key for improving throughput and for reducingco-channel interference in Wi-Fi networks.In the co-channel interference test, the ZyXEL smart-antenna-equipped AP performed 75% better on average over theAruba device. In fact, the single ZyXEL AP outperformed two Aruba APs.Study Confirms that ZyXEL Smart Antenna AP is the Best SolutionIncreased use of mobile applications and demand forThe second test, conducted at the University of Brescia,wireless service has been matched by steady growth in thesimulates overt co-channel interference in large-venuenumber of mobile devices. To keep pace with this demand,deployments. To be objective, four pairs of APs wereWLAN infrastructures must offer more throughput andconfigured to transmit at 17 dBm, and each AP washigher data speeds. Currently, the 802.11ac wirelessindividually deployed in a separate room on the samestandard with its superior bandwidth, MIMO, and denserfloor, surrounded by four clients. The total aggregatemodulation offers the best wireless solution for modernthroughput for the four clients is calculated in four separatevenues. In addition to standard features offered, everydeployments. On average, the ZyXEL devices demonstratedvendor pays close attention to optimized antenna design.a 70% performance advantage. To determine whetherZyXEL and Ruckus concurrently introduced AP productssmart-antenna technology addresses the co-channelthat adopt smart-antenna technology.interference issue even at higher transmission powerlevels, the university executed a similar test in whichThe coverage performance test results demonstrate thattransmission power was increased 4 times to 23 dBm forthe smart-antenna APs from Ruckus and ZyXEL see gainsthe access points equipped with smart antennas. Theof 60% and 35% respectively when compared to productsother devices were maintained at 17 dBm, which shouldfrom Cisco and Aruba in deployments with significantwith advantage with less co-channel interference. Evenphysical obstacles — like concrete or brick walls —under such conditions, ZyXEL outperformed the other APsbetween the AP and client. The performance of the Ruckusin all four deployments. This confirmed that ZyXEL smart-AP, however, falls off sharply at 2.4 GHz, and is barely ableantenna technology stood out in the most demanding Wi-to connect with the client in some locations.Fi environments.3

Conduct and Procedure of The ExperimentThis experiment was conducted with the assistance of theperformance at the physical and media-access control layers.Wireless Networking Group of the University of Brescia,Research activities include the opportunistic exploitationa professional outreach unit that focuses on wirelessof 802.11 networks for localization, jamming, and pseudo-networking. The group specializes in analysis, design, anddeterministic channel algorithms.experimental characteristics related to wireless networkCoverage TestThis test was designed to determine if access points adoptingnearby rooms. Each is configured to experience differentsmart-antenna technology achieve higher throughput inlevels of reflection from single and multiple sources. Tomulti-reflective environments, and whether performance inavoid the bias of reciprocal orientation of the APs, the testthese situations directly impacts user experience.is run twice for each of the four rotations — 0, 90, 180, 270degrees. The final result is obtained by picking the bestThe access point in this test is deployed in a room withresult from two outcomes and calculating the average overan open floor plan, while 10 clients are located in severalthe four rotations.Access PointClient NodeClient Node difficult to reachConcrete 23132.4G5G2120518195G8 459104222.4G5G5G4734827142.4G461516175G1AP5mFigure 1 The deployment of coverage test; ZyXEL ranks no.1 in the most positionsAs shown in the following figures, the first- and second-best performance was achieved by Ruckus and ZyXEL devices inalmost every category. This reflects the benefits of the smart antenna, with ZyXEL’s smart antenna boosting performanceby 60% at both 5 GHz and 2.4 0sumgainTable1 The result at 5 7046.9526.62273.2910%Table2 The result at 2.4 .6566%

Co-channel Interference TestThe mainstream popularity of the 802.11ac standard brings with it the potential issue of a lack of available channels inthe 80/160 MHz range. Therefore, co-channel interference is an unavoidable consequence of 802.11ac when planningdeployments in large venues or high-density Wi-Fi environments. The co-channel test reveals the potential benefits ofsmart-antenna technology in such scenarios.Phase 1A pair of access points from the same vendor wereTable 5 shows the total aggregate throughput recordeddeployed in two nearby rooms, as shown in figure 4, andin the four deployments for each vendor. In the first threeboth are configured at 80 MHz on channel 157 at 17 dBmdeployments, ZyXEL stands out with an advantage rangingtransmission power. In this setup, the interference impactfrom 25.5% to 46.7% over the second-best performer, Cisco.of the two APs should be identical, as they share the sameOnly in the fourth deployment does Cisco perform better,channel. Each AP services four associated clients, which arewith a 14.6% advantage over ZyXEL. However, unlike thedeployed in four different configurations to avoid test bias.first test, fellow smart-antenna adopter Ruckus did notThis test is designed to recreate a realistic usage scenarioshow significant advantage in a co-channel environment.and monitor the TCP transport traffic of eight clients atonce.252423455 AP#2756786222120192518Access 613171324488141527161173AP#1AP#14Figure 2 & 3 The four deployments of co-channel interference (1)The aggregate throughput(Mbps) e 4 The result of co-channel interference (1)54746AP#2813Client Node231324

Phase 2Drawing upon the findings of phase 1, phase 2 creates aare maintained at 17 dBm. In this phase — a much moresimilar test. Transmission power is adjusted up todemanding environment — the two smart-antenna APs23 dBm on both the Ruckus and ZyXEL devices — the twoare tested to see whether they demonstrate a significantaccess points with smart antennas — while the othersperformance advantage.Access Point25242322212019182524Client Node2322Concrete2120Brickwall1918845 545 711AP#131AP#134234Figure 5 & 6 The four deployments of co-channel interference (2)The aggregate throughput(Mbps) .62391.25574.11295.94444.03366.35546.64Figure 7 The result of co-channel interference (2)Fo r m o re p ro d u c t i n fo r m at i o n , v i s i t u s o n t h e we b at w w w. Zy X E L . co mCopyright 2016 ZyXEL Communications Corp. All rights reserved. ZyXEL, ZyXEL logo are registered trademarks of ZyXEL CommunicationsCorp. All other brands, product names, or trademarks mentioned are the property of their respective owners. All specifications are subjectto change without notice.5-000-0071600408/16

Study Confirms that ZyXEL Smart Antenna AP is the Best Solution Vendor Aruba Cisco Ruckus ZyXEL Model name AP-225 2702i R700 WAC6503D-S PHY 802.11ac 802.11ac 802.11ac 802.11ac Spatial streams 3x3:3 3x4:3 3x3:3 3x3:3 Radio Dual radio Dual radio Dual radio Dual radio Smart antenna - - Yes Yes t