The use of lte in unlicensed spectrum generates multiple challenges 2. Two lte wifi coexistence technologies of note include lte unlicensed lte u and licensed authorized access laa. The con is if you are competing for bandwidth or the backhaul stinks or if there is interference on the wifi, then there are issues. Performance analysis for coexistence of ltelaa and wifi systems. The simple fact is that if you deploy an lte u base station near a wifi access point set to the same channel, there will be interference, with a corresponding negative impact on performance. Crosstechnology interference nulling for improved lteuwifi. Software based implementation of ltewifi aggregation and its impact on higher layer protocols. Resolving interference in a crowded wifi environment using. I just recently moved and had to get these from tmobile because i get 1 bar of 4g by the window and the entire rest of the apartment is emergency only an ideal use case for the devices, really however i have an asus rtac66u and the only 5ghz wireless network around at all. This works with your existing wifi, its just an upgrade the carrier has to do on their system and a software upgrade in your smartphone. For most wifi and lte u small cell deployments channel selection is usually sufficient to meet the coexistence requirements. How local governments wifi networks will contend with. Lteu is a wireless network technology thats promising a lot, as well as ruffling a few feathers especially in the wifi world. When your devices use wifi to connect to internet the signals are sent with radio waves and despite of all advanced features wireless interference can happen.
Moreover, interference from lte u with moderate power can be even more harmful to wifi than highpower interference. In wifi, there is a politeness protocol that lte lacks, which means that wifi will back off if it senses interference from other users. In existing lte u systems, the lte base station enb estimates the fair portion. Towards lte u interference detection, assessment and mitigation in 802. Lte u uses first as coexistence mechanism the dynamic channel selection dcs approach where the lte u bs seeks for a clear. Lte u and wifi coexistence are a relatively new area of research.
Coordinated dynamic spectrum management of lteu and wi. In fact, the wifi alliance is trying to convince the fcc that it should approve all lte u products, just as if the lte u gear were wifi gear. On practical crosstechnology interference nulling for lte u wifi coexistence. Can lteu forum specification provide fair coexistence. To realize unlicensed operation without major changes to the lte design, an industry initiative lte u forum proposed an unlicensed lte variant, known as lte u. If lte is allowed in this frequency, it might bully wifi and take over the band. Two lte wifi coexistence technologies of note include lteunlicensed lteu and licensed authorized access laa. Without proper coexistence mechanisms, lteu transmissions could cause considerable interference on wifi network relative to wifi.
And it was designed to work using unlicensed spectrum and to be a good neighbor to other technologies sharing the unlicensed bands. As a consequence, the bs is able to increase its csat duty cycle bayhan2017coexistence. The lte u standard is based on the duty cycle, while lte laa is based on listenbeforetalk lbt. Aug 31, 2015 lteu stands for lteunlicensed, referring to its connectivity in the unlicensed 5ghz spectrum. Education in the frame of the national sustainability program under grant. We propose wiplus a system that enables wifi to deal with the stealthy invasion of lte u into the frequency bands used by wifi. On practical crosstechnology interferencenulling for lteuwifi coexistence.
The group this month asked the fcc to avoid authorizing any lte u equipment until the wifi alliance is able to conduct its own tests on vendor devices using new interference. Simulating lte and wifi coexistence in unlicensed spectrum arxiv. The lte u dl signal impacts the wifi communication in three ways, namely, 1 blocking medium access by triggering the energy detection ed physical carrier sense cs mechanism of wifi or 2 corrupting packets due to cochannel interference from lte u. Lte u wifi coexistence can be significantly improved by placing socalled coexistence gaps in space through crosstechnology interference nulling ctin from lte u bs towards wifi nodes. Coordinated dynamic spectrum management of lteu and wifi. There will be cases where lteu operation and wifi use different channels and under these circumstances there will be only minimal levels of interference.
The lte u dl signal may or may not impact the wifi communication in three ways, namely, 1 blocking medium access by triggering the energy detection ed physical carrier sense cs mechanism of wifi or 2 corrupting packets due to cochannel interference from lte u. Lteuwifi coexistence can be significantly improved by placing socalled coexistence gaps in space through crosstechnology interferencenulling ctin from lteu bs towards wifi nodes. The lteu standard is driven by alcatellucent, ericsson, lg electronics, and qualcomm technologies inc. It is suggested in 3gpp that lteu will be used for supplemental downlink while the uplink will continue to use licensed spec trum. Enabling crosstechnology communication between lte. Blocking medium access by triggering the energy detection ed physical carrier sense cs mechanism of wifi strong interference level 62 dbm corrupting packets due to cochannel interference from lteu. Abstract lte technologies for unlicensed spectrum are gaining both attention and momentum within various regulatory bodies european cept, us fcc, standards groups 3gpp, etsi and industry fora wifi. Before the interference controversy threatened to delay deployments, tmobile was expected to use the technology on its smartphones by. System model wifi aps surrounded by multiple lteu cells.
It makes the handoff to the lte carrier much more efficient for the ran. Its mandatory for wifi to use two different thresholds for channel. From an interference management perspective, laa is much more efficient due to the signaling. Would lteu devices interfere with existing wifi and vice versa.
In xii, we discuss previous work on this topic and distinguish our work from the existing literature. The lteu system is being designed to overcome this issue and using an listen before transmit, lbt solution, all users should be able to coexist without any undue levels of interference. Interference can occur within a device or between devices, including between wireless carrier signals or between wireless standards. Wifi lte u coexistence testing wifi apclient pair running tcpudp over a 20 mhz channel in u nii3, with a.
Interference nulling for improved intertechnology coexistence in lteu and wifi networks authors. Wifi vendor approach is to increase density of wifi aps to overcome the noise by client devices simply being closer to the ap. Aug 27, 2015 verizon has said it intends to deploy lte u in 5ghz in 2016. Lteu enables 4g lte radio communication technology in unlicensed spectrum, 5 ghz band. Suzan bayhan, piotr gawlowicz, anatolij zubow, and adam w. Lteu is a system for running lte networks in some of the unlicensed frequencies used by wifi. Lte, wifi, and wigig push filter capabilities microwaves. The increasing number of mobile devices results in an. The lte u standard is driven by alcatellucent, ericsson, lg electronics, and qualcomm technologies inc.
To be able to cope with this impact and its effects, an approach that fist, enables wifi to detect the lteu interference and second, enables to quantify the effective available medium airtime of each link downlink and uplink during runtime, is needed. Other wireless devices any wireless device can technically be the reason for a signal interference. Software defined is the prevalent buzzword adjective in many areas of. Lteu is a 4g wireless technology that wireless operators are planning to deploy to add more capacity to networks. Lteu dl trac creates interference on wifi dl and ul trac. So yes, lte u can negatively affect wifi performance. The main goal of this work is to enable cooperation between colocated lteu bss and wifi aps operating in the same 5ghz band and being owned by di erent authorities.
Mar 22, 2017 but your wifi connection may pay the price, due to lteu interference with 5ghz wifi thanks to a recent regulatory decision, wireless companies like verizon and tmobile will soon be transmitting data in the same part of the public airwaves thats used by wifi. Lte u is required to have dfs in areas of the 5ghz spectrum, but theres no confirmation yet on whether lte u will incorporate dfs and not impact nearby wifi hotspots. Abstract lte in unlicensed lteu constitutes a new source of interference in the 5ghz ism band with a potentially strong impact on wifi performance. Towards lteu interference detection, assessment and mitigation in. New compromises wont end the fight between lteu and wifi.
These can be wireless speakers, baby monitors, garage door openers, etc. Using solely mac layer information extracted passively, during runtime, out of the hardware registers of the wifi nic at the wifi access point, wiplus is able to. Lteu isnt intended to replace existing lte connectivity, but supplement its speed and services. Considering a duty cycle period which extends wifi system slots refer to figure 1 the enb or ue in lte u subsystem transmits during the lte u on. Lte over wifi spectrum sets up industrywide fight over. The lteu dl tra c creates interference on wifi dl and ul tra c. Washingtonthere are a growing number of cases where there has been actual or alleged interference to 4g lte installations. Consider an infrastructurebased wifi network coexisting with an lte u network on the same unlicensed band, where interference is coming from lte u subsystem to the wifi station labeled staa. Crosstechnology communication for rrm between lteu.
The two standards, lte u and lte laa, for lte to coexist with wifi on the 5ghz band have evolved. A performance boost from combining wifi and lte unlicensed 30. Jan 06, 2016 simulation results show that considered lte interference waveform generates colorednoise like effect on wifi receivers, and is less harmful on wifi detection performance than fullband white noise given the same power. The main goal of this work is to enable cooperation between colocated lteu bss and wifi aps operating in the same. The vendor in question sounds like theyre looking to push lteu to corporate users as a future wifi replacement offering. Pdf we propose wiplus a system that enables wifi to deal with the stealthy invasion of lte u into the frequency bands used by wifi. Lteu is being developed outside of the 3gpp standards process, even though the same companies in the lteu forum are also active in 3gpp. Wiplus does not require any modifications to the wifi client stations and works with commodity wifi aps where it has a simple software installation process.
Advanced filters are necessary to prevent interference and maintain adequate signal integrity as interference increases. Towards lteu interference detection, assessment and. Wifi is a very advanced technology, a magic of its kind. The lteu dl traffic creates interference on wifi bss dl and ul traffic. Coexistence of lteu and wifi with direct communication. The fundamental problem here is that lte u does not listen before talk, a most basic politeness protocol. Previous works in this area are summarized as follows. Free and open source lte software suite developed by software radio systems. Figure 22 channel selection for lte u sdl transmission the interference level in a channel is initially measured by energy detection, which is. Moreover, interference from lteu with moderate power can be even more harmful to wifi than highpower interference.
Background on lte u, wifi, and interference nulling. This makes the deployment even more challenging as the des do not transmit in unlicensed spectrum yet experience interference from wifi transmissions. Impact of lteu on wifi the lteu dl signal may or may not impact wifi communication in three ways. On practical crosstechnology interferencenulling for. Lteu forum and coexistence overview welcome to mentor. Wifi influence on lte downlink data and control channel. It will serve as an alternative to carrierowned wifi hotspots. The most common interference scenario is bluetooth and lte. Lteu, an emerging technology that aims to reduce cell phone data congestion by offloading traffic onto unlicensed spectrum, has been a hot topic in the wireless world. Software based implementation of lte wifi aggregation and its impact on higher layer protocols. Simultaneous operation of these radios in adjacent frequency bands causes interference that can degrade performance and throughput. Although it is not magic of course but a logically explainable effect of radio waves. Sep 08, 2015 lteu this is literally running the lte format in the wifi spectrum. Lte u features what consumers like about 4g lte mobile broadband.
Therefore, we focus on the impact of lte u interference on wifi performance in this paper. Lte u wifi coexistence with cablelabs wifi now episode. Impact of lte operating in unlicensed spectrum on wifi using. The lteu dl signal may or may not impact the wifi communication in three ways, namely, 1 blocking medium access by triggering the energy detection ed physical carrier sense cs mechanism of wifi or 2 corrupting packets due to cochannel interference from lteu. Investigating interference between 4g lte and broadcast. So much to my surprise when i started to get massive interference and drops right after getting the signal boosters. The most common interference scenario is bluetooth and lte with wifi because these technologies are so widespread. Lteu is intended to let cell networks boost data speeds over short distances, without requiring the user to use a separate wifi network as they normally would.
Our solution, named xzero, achieves this goal for the particular case of lteunlicensed lteu and wifi by overcoming the challenges of crosstechnology interference nulling by a null search at the lteu bs with assistance from the wifi network. The battle between lte and wifi may have left lteu out in. To be able to cope with this impact and its effects, an approach that fist, enables wifi to detect the lte u interference and second, enables to quantify the effective available medium airtime of each link downlink and uplink. Lteuwifi coexistence with cablelabs wifi now episode. In order to enable lte operation in unlicensed spectrum, a new band was defined in the oai software, which uses the same center frequency as wifi channel 6. Wifi, and ltelaa systems, the 3dmcat software process is shown in fig. Fellah has been a member of the program advisory board for the 4g world.
The main objective of xzero is to improve the coexistence between colocated lte u and wifi networks. There are technologies in development to help lte u and wifi coexist, but also a lot of doubt on both sides and testing is ongoing. To this end, it performs at the lte u bs interference nulling towards colocated wifi nodes fig. Dec, 2015 in fact, the wifi alliance is trying to convince the fcc that it should approve all lte u products, just as if the lte u gear were wifi gear. From indevice to lte and bluetooth interference can occur within a device or between devices, including between wireless carrier signals or between wireless standards. Comprehensive spectrum management for heterogeneous.
And it is taking an entirely different approach to coexistence, using a carriercontrolled onoff switch known as duty cycling instead of reliably fair listenbeforetalk. The lteu dl signal impacts the wifi communication in three ways, namely, 1 blocking medium access by triggering the energy detection ed physical carrier sense cs mechanism of wifi or 2 corrupting packets due to cochannel interference from lteu. Moderate power interference from lte u can be even more detrimental to wifi than highpower interference. With lte unlicensed using 5 ghz spectrum becomes increasingly important to. Lteu cellular signals could mean slower wifi 4g lte networks. Wifi is designed to be interference tolerant to operate in unlicensed bands.
Wifi ap intertechnology interference lteu bs wifi ap wifi ap fig. More wireless and telecommunications standards are flooding the spectrum with dense and high speed data channels. Blocking medium access by triggering the energy detection ed physical carrier sense cs mechanism of wifi strong interference level 62 dbm corrupting packets due to cochannel interference from lte u. The main goal of this work is to enable cooperation between colocated lteu bss and wifi aps operating in the same 5ghz band and being owned by dierent authorities. Lteu, wifi backers wrangle with fcc over sharing spectrum. Zigbee and wifi interference and coexistence duration. A simulation study of the lte interference on wifi signal. The battle between lte and wifi may have left lte u out in the cold after a long fight over lte u, some carriers may go straight to the less controversial laa anyway. These situations have occurred largely at colocated transmitter sites where fm stations and wireless carriers share the same site or the same tower. The technology lets the carriers use the same lte technology they have running in their licensed spectrum bands in unlicensed spectrum bands, including 2. The results show that both wifi and lte networks cause significant interference to each other and that the degradation is dependent on a number of factors such as power levels and physical topology. Coexistence gaps in space via interference nulling for lte. We suggest that lteu bss equipped with multiple antennas can create coexistence gaps in space domain in addition to the time domain gaps by means of crosstechnology interference nulling towards wifi nodes in the interference range. Question i just recently moved and had to get these from tmobile because i get 1 bar of 4g by the window and the entire rest of the apartment is emergency only an ideal use case for the devices, really.
It is also possible to run lteu and wifi on the same channel. Impact of lte u on wifi the lte u dl signal may or may not impact wifi communication in three ways. In xiii, we propose an analytical model to characterize the interference between wifi and lte networks followed by partial experimental validation of. Lte in unlicensed spectrum lte u lte u is a proposal, originally developed by qualcomm, for the use of the 4g lte radio communications technology in unlicensed spectrum, such as the 5 ghz band used by 802. The workshop, the latest of several intended to make sure lteu doesnt unfairly interfere with. In unlicensed spectrum, lteu will suffer interference as well.