Coexistence of stations capable of different modulation schemes in a wireless local area network
AssigneeKoninklijke Philips Electronics N. V.
InventorsSunghyun Choi, Olaf Josef Hirsch, Atul Garg, Javier del Prado Pavon
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Abstract
A local-area network is provided where OFDM stations and DSSS/CCK-only stations coexist. A beacon signal having a contention-free-period (CFP) is transmitted from an access point to the plurality of said stations. The OFDM-modulated data is transmitted to the plurality of stations before the CFP ends, and after the CFP period ends, the DSSS/CCK-modulated data is transmitted, thereby preventing collisions between the stations.
Claims22
A wireless-local-area network comprising:
- at least one access point capable of transmitting and receiving data modulated using a first modulation scheme and a second modulation scheme;
- at least one first station capable of transmitting and receiving data modulating using the first modulation scheme;
- and,
- at least one second station capable of transmitting and receiving data modulated using the second modulation scheme,
- wherein said access point transmits data modulated using the first modulation scheme if the transmission of data modulated according to the first modulation scheme is possible before the CFP expires and transmits data modulated according to the second modulation scheme after the contention-free-period ends.
A method for providing a communication between an access point and a plurality of stations having at least one first station and at least one second station in a wireless-local-area network (WLAN), the method comprising the steps of:
- transmitting a beacon signal having a contention-free period (CFP) followed by a contention period (CP) to the plurality of said stations;
- determining whether a transmission of OFDM-modulated data is possible before the CFP expires;
- if so, transmitting the OFDM-modulated data to the plurality of said stations;
- and, transmitting DSSS/CCK-modulated data during the contention period (CP).
A system comprising:
- a first station capable of transmitting and receiving data modulated using a first modulation scheme;
- a second station capable of transmitting and receiving data modulated using a second modulation scheme;
- and,
- an access point for communicating with the first and the second stations,
- wherein the access point transmits a beacon frame indicating a beginning of a contention-free period followed by a contention period, and the contention-free period comprises a sub-contention period before the contention-free period expires during which the second station is enabled to transmit data modulated according to the second modulation scheme.
A station in a local-area network, the station being capable of transmitting and receiving data using a first modulation scheme, the local-area network further comprising a second station capable of transmitting and receiving data using a second modulation scheme and an access point for communicating with both stations, wherein the station receives a beacon frame transmitted by the access point indicating the beginning of a contention-free period followed by a contention period, and the contention-free period comprises a sub-contention period before the contention-free period expires during which the second station is enabled to transmit data modulated according to the second modulation scheme.
Dependencies are inferred from the claim text.