Method for adapting a link for selecting a frame transmission mode and corresponding WI-FI access point

• US 9,839,052 B2
• Filed: 06/30/2014
• Issued: 12/05/2017
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Bouzigues, Marc-Antoine, Siaud, Isabelle, Ulmer-Moll, Anne-Marie
• Primary Examiner(s): Smarth, Gerald
• Application Number:
  US14/901,347
• Publication Number:
  US 20160157269A1
• Time in Patent Office: 1,254 Days
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04W 28/0205 at the air interface dynamic wireless traffic scheduling H04W72/12
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

A link adaptation method uses a selection criterion for selecting a transmission mode for transmitting PPDU frames over a channel of a telecommunications system. The system includes an access point and a plurality of stations having various different transmission modes associated with different data rates. Access to the channel being of the random type. The selection makes use of a time occupancy metric γ of the channel.

Claims

1. A link adaptation method comprising:

using a selection criterion for selecting a transmission mode for transmitting physical layer protocol data unit (PPDU) frames to be transmitted over a channel of a telecommunications system having an access point and at least one station possessing various transmission modes associated with different instantaneous bit rates, access to the channel being of the random type, wherein selecting a transmission mode makes use of a time occupancy metric γ

for the channel that is expressed in the following form;

2. The link adaptation method according to claim 1, wherein the time determination for determining the mean access time to the channel t_acc is performed from a transmission mean data rate.

3. The link adaptation method according to claim 2, wherein the mean data rate is expressed as a function of the probability of successfully transmitting the PPDU frames associated with a service n, said probability of success P_S(G) being estimated as follows:

4. The link adaptation method according to claim 1 comprising:

comparing a threshold value with the values of the metric γ

as determined for different transmission modes in order to preselect modes; and

selecting in compliance with a determined criterion of one mode from among the various preselected modes.

5. The link adaptation method according to claim 1, wherein occupancy of the channel is measured over a determined observation window and makes use of a Poisson distribution model for the arrival rates of the PPDU frames to be transmitted, the variance λ

of the Poisson distribution corresponding to the mean frequency of arrival of the PPDU frames.

6. The link adaptation method according to claim 1, wherein the various transmission modes are classified by groups of equivalent data rates D, and for a group, the method comprises:

determining the value of a first metric α

for a given transmission mode, which metric measures relative degradation of the communication signal at a given distance d as introduced by the transmission medium for a given environment relative to a reference model of the transmission medium, resulting from a multi-path effect and/or an attenuation effect of the transmission medium; and

comparing values of the first metric α

for different modes for selection with at least one transmission mode (Mode_i) per group.

7. A WiFi access point comprising:

M transmission modes that are associated with respective different instantaneous data rates, M≧

2, for a telecommunications system having a plurality of stations and the access point, access to the transmission channel of the WiFi telecommunications system being of the random type;

a non-transitory computer-readable medium comprising instructions stored thereon;

a processor configured by the instructions to perform acts comprising;

determining the value of a first time occupancy metric γ

_n,m of the channel for a given transmission mode, which metric is expressed in the following form;

8. A telecommunications system including a WiFi access point according to claim 7.

9. A non-transitory computer-readable data medium including program instructions adapted to perform a link adaptation method, when said program is loaded and executed in a WiFi access point the link adaptation method comprising:

using a selection criterion for selecting a transmission mode for transmitting physical layer protocol data unit (PPDU) frames to be transmitted over a channel of a telecommunications system having an access point and at least one station possessing various transmission modes associated with different instantaneous bit rates, access to the channel being of the random type, wherein selecting a transmission mode makes use of a time occupancy metric γ

for the channel that is expressed in the following form;