Maximizing LTE Capacity in Unlicensed Bands (LTE-U/LAA) While Fairly Coexisting With 802.11 WLANs

Valls, Víctor; García‐Saavedra, Andrés; Costa, Xavier Pérez; Leith, Douglas J.

doi:10.1109/lcomm.2016.2557320

Cited by 44 publications

(23 citation statements)

References 5 publications

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“…Two key features of WiFi systems relevant to our work are: (i) each 802.11 packet includes in the header information regarding the duration of the transmission, i.e., upon correct reception of a packet, a station knows the duration for which the channel will be busy; (ii) after a successful transmission all stations in the network wait for an Arbitration Inter-Frame Spacing (AIFS) time of at least 34 µs. 3 That is, importantly, after each successful transmission there will be at least 34 µs during which the channel is free of WiFi transmissions. III.…”

Section: B Ieee 80211 Mac Protocol (Wifi)mentioning

confidence: 99%

ORLA/OLAA: Orthogonal Coexistence of LAA and WiFi in Unlicensed Spectrum

García‐Saavedra¹,

Patras

Valls

et al. 2018

IEEE/ACM Trans. Networking

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Future mobile networks will exploit unlicensed spectrum to boost capacity and meet growing user demands costeffectively. The 3GPP has recently defined a Licensed-Assisted Access (LAA) scheme to enable global Unlicensed LTE (U-LTE) deployment, aiming at (i) ensuring fair coexistence with incumbent WiFi networks, i.e., impacting on their performance no more than another WiFi device, and (ii) achieving superior airtime efficiency as compared to WiFi. In this paper we show the standardized LAA fails to simultaneously fulfill these objectives, and design an alternative orthogonal (collision-free) listen-beforetalk coexistence paradigm that provides a substantial improvement in performance, yet imposes no penalty on existing WiFi networks. We derive two LAA optimal transmission policies, ORLA and OLAA, that maximize LAA throughput in both asynchronous and synchronous (i.e., with alignment to licensed anchor frame boundaries) modes of operation, respectively. We present a comprehensive performance evaluation through which we demonstrate that, when aggregating packets, IEEE 802.11ac WiFi can be more efficient than 3GPP LAA, whereas our proposals can attain 100% higher throughput, without harming WiFi. We further show that long U-LTE frames incur up to 92% throughput losses on WiFi when using 3GPP LAA, whilst ORLA/OLAA sustain >200% gains at no cost, even in the presence of non-saturated WiFi and/or in multi-rate scenarios.

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Section: B Ieee 80211 Mac Protocol (Wifi)mentioning

confidence: 99%

ORLA/OLAA: Orthogonal Coexistence of LAA and WiFi in Unlicensed Spectrum

García‐Saavedra¹,

Patras

Valls

et al. 2018

IEEE/ACM Trans. Networking

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“…Although the throughput in this case is not as reduced as with CSAT, the performance degradation is considerable. One way to alleviate this in LBE might be for the LTE to transmit before the DIFS to allow WiFi stations to decode the CTS-to-self, similarly to the approach described in [36], but this is outside the scope of the present paper.…”

Section: F Example: Lte and Wifi With Virtual Carrier Sensingmentioning

confidence: 99%

Fair Coexistence of Scheduled and Random Access Wireless Networks: Unlicensed LTE/WiFi

Cano

Leith

García‐Saavedra³

et al. 2017

IEEE/ACM Trans. Networking

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Abstract-We study the fair coexistence of scheduled and random access transmitters sharing the same frequency channel. Interest in coexistence is topical due to the need for emerging unlicensed LTE technologies to coexist fairly with WiFi. However, this interest is not confined to LTE/WiFi as coexistence is likely to become increasingly commonplace in IoT networks and beyond 5G. In this article we show that mixing scheduled and random access incurs and inherent throughput/delay cost, the cost of heterogeneity. We derive the joint proportional fair rate allocation, which casts useful light on current LTE/WiFi discussions. We present experimental results on inter-technology detection and consider the impact of imperfect carrier sensing.

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“…In the one hand a time sharing approach between LTE and Wi-Fi, this method called LTE-U (non 3GPP standard) is based on duty-cycle coexistence. The LTE-U system is tuned on during a period of time and turned off for the rest of the cycle [22], [23]. In the other hand, two standardized access procedures were proposed by 3GPP: LTE Wi-Fi link Aggregation (LWA) and LAA.…”

Section: Lbt Enhancementmentioning

confidence: 99%