Embodiments of a system and methods for distinguishing high-efficiency Wi-Fi (hew) packets from legacy packets are generally described herein. In some embodiments, an access point may select a value for the length field of a legacy signal field (l-SIG) that is non-divisible by three for communicating with hew stations and may select a value for the length field that is divisible by three for communicating with legacy stations. In some embodiments, the access point may select a phase rotation for application to the BPSK modulation of at least one of the first and second symbols of a subsequent signal field to distinguish a high-throughput (HT) ppdu, a very-high throughput (VHT) ppdu and an hew ppdu.
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1. An access point (AP) arranged for communicating with a plurality of stations (STAs) including high-efficiency Wi-Fi (hew) stations and legacy stations, the access point comprising hardware processing circuitry and physical layer (PHY) circuitry to:
configure a packet protocol data unit (ppdu) comprising a legacy signal field (l-SIG) following legacy training fields, the l-SIG including at least a length field and a rate field;
select a value for the length field that is not-divisible by three for communicating with the hew stations; and
select a value for the length field that is divisible by three for communicating with at least some of the legacy stations.
13. A high-efficiency Wi-Fi (hew) station arranged to distinguish an hew packet protocol data unit (ppdu) from a non-hew ppdu, the hew station comprising hardware processing circuitry and physical layer (PHY) circuitry configured to:
receive a legacy signal field (l-SIG) following legacy training fields, the l-SIG including at least a length field and a rate field;
determine whether a value for the length field is divisible by three;
verify a parity bit of the l-SIG;
identify the ppdu as an hew ppdu when the value in the length field is not divisible three and the parity bit is verified; and
identify the ppdu as a non-hew ppdu when the value in the length field is divisible three and the parity bit is verified.
10. An access point arranged for communicating with a plurality of stations including high-efficiency Wi-Fi (hew) stations and legacy stations, the access point comprising hardware processing circuitry and physical layer (PHY) circuitry to configure a packet protocol data unit (ppdu) comprising:
a legacy signal field (l-SIG) following one or more legacy training fields; and
one or more fields following the l-SIG including a subsequent signal field, the subsequent signal field having first and second symbols that have BPSK modulation,
wherein the access point is further arranged to select a phase rotation for application to the BPSK modulation of at least one of the first and second symbols of the subsequent signal field to distinguish a high-throughput (HT) ppdu, a very-high throughput (VHT) ppdu and an hew ppdu.
17. A method performed by an access point for communicating with a plurality of stations including high-efficiency Wi-Fi (hew) stations and legacy stations, the method comprising:
configuring a packet protocol data unit (ppdu) comprising a legacy signal field (l-SIG) following legacy training fields, the l-SIG including at least a length field and a rate field;
selecting a value for the length field that is not-divisible by three for communicating with the hew stations; and either
selecting a value for the length field that is divisible by three for communicating with at least some of the legacy stations; or
selecting a phase rotation for application to BPSK modulation of at least one of first and second symbols of a subsequent signal field to distinguish a high-throughput (HT) ppdu, a very-high throughput (VHT) ppdu and an hew ppdu.
15. A high-efficiency Wi-Fi (hew) station arranged to distinguish an hew packet protocol data unit (ppdu) from a non-hew ppdu, the hew station comprising hardware processing circuitry and physical layer (PHY) circuitry configured to:
receive a legacy signal field (l-SIG) following legacy training fields, the l-SIG including at least a length field and a rate field;
receive a subsequent signal field, the subsequent signal field having first and second symbols that have BPSK modulation,
determine whether the ppdu is a high-throughput (HT) ppdu, a very-high throughput (VHT) ppdu or an hew ppdu based on the phase rotation applied to the BPSK modulation of at least one of the first and second symbols of the subsequent signal field,
wherein for an hew ppdu, a ninety-degree phase rotation is applied to the BPSK modulation of the first symbol and no phase rotation is applied to the BPSK modulation of the second symbol of the subsequent signal field.
19. A non-transitory computer-readable storage medium that stores instructions for execution by one or more processors of an access point to perform operations for communicating with a plurality of stations including high-efficiency Wi-Fi (hew) stations and legacy stations, the operations to configure the access point to:
configure a packet protocol data unit (ppdu) comprising a legacy signal field (l-SIG) following legacy training fields, the l-SIG including at least a length field and a rate field;
select a value for the length field that is not-divisible by three for communicating with the hew stations; and either
select a value for the length field that is divisible by three for communicating with at least some of the legacy stations; or
select a phase rotation for application to BPSK modulation of at least one of first and second symbols of a subsequent signal field to distinguish a high-throughput (HT) ppdu, a very-high throughput (VHT) ppdu and an hew ppdu.
2. The access point of
3. The access point of
wherein the access point is further arranged to select a phase rotation for application to the BPSK modulation of at least one of the first and second symbols of the subsequent signal field to distinguish a high-throughput (HT) ppdu, a very-high throughput (VHT) ppdu and an hew ppdu.
4. The access point of
5. The access point of
wherein for communicating with HT stations, the subsequent signal field is an HT signal field (HT-SIG) and the access point is arranged to apply a ninety-degree phase rotation to the BPSK modulation of both the first symbol and the second symbol of the HT-SIG, and
wherein for communicating with non-HT stations, the access point is configured to refrain from including the subsequent signal field following the l-SIG.
6. The access point of
7. The access point of
wherein the access point is configured to multiply the ceiling function by three and subtract three to calculate the value for the length field for non-hew stations.
8. The access point of
configure the ppdu as an hew ppdu to include a number of long-training fields (LTFs), the number of LTFs being based on a maximum number of streams communicated over a link;
contend for a wireless medium during a contention period to receive control of the medium for an hew control period; and
transmit the hew ppdu during the hew control period, wherein during the hew control period, the access point operates as a master station having exclusive use of the wireless medium for communication of data with a plurality of scheduled hew stations in accordance with a non-contention based scheduled orthogonal frequency division multiple access (OFDMA) technique in accordance with signaling information indicated in the hew-SIG,
wherein the scheduled OFDMA technique is one of an uplink OFDMA technique, a downlink OFDMA technique or a multi-user multiple-input multiple-output (MU-MIMO) technique.
9. The access point of
wherein the links of the hew ppdu are configurable to have a bandwidth of one of 20 MHz, 40 MHz, 80 MHz or 160 MHz.
11. The access point of
12. The access point of
wherein for communicating with HT stations, the subsequent signal field is an HT signal field (HT-SIG) and the access point is arranged to apply a ninety-degree phase rotation to the BPSK modulation of both the first symbol and the second symbol of the HT-SIG, and
wherein for communicating with non-HT stations, the access point is configured to refrain from including the subsequent signal field following the l-SIG.
14. The hew station of
decode subsequent fields of the ppdu when the ppdu identified as an hew ppdu, and
refrain from decoding subsequent fields of the ppdu when the ppdu is identified as a non-hew ppdu.
16. The hew station of
wherein the hew station is further configured to communicate with an hew master station in accordance with a scheduled OFDMA technique based on information received in the hew-SIG.
18. The method of
configuring the ppdu as an hew ppdu to include a number of long-training fields (LTFs), the number of LTFs being based on a maximum number of streams communicated over a link;
contending for a wireless medium during a contention period to receive control of the medium for an hew control period; and
transmitting the hew ppdu during the hew control period, wherein during the hew control period, the access point operates as a master station having exclusive use of the wireless medium for communication of data with a plurality of scheduled hew stations in accordance with a non-contention based scheduled orthogonal frequency division multiple access (OFDMA) technique in accordance with signaling information indicated in the hew-SIG,
wherein the scheduled OFDMA technique is one of an uplink OFDMA technique, a downlink OFDMA technique or a multi-user multiple-input multiple-output (MU-MIMO) technique.
20. The non-transitory computer-readable storage medium of
configure the ppdu as an hew ppdu to include a number of long-training fields (LTFs), the number of LTFs being based on a maximum number of streams communicated over a link;
contend for a wireless medium during a contention period to receive control of the medium for an hew control period; and
transmit the hew ppdu during the hew control period, wherein during the hew control period, the access point operates as a master station having exclusive use of the wireless medium for communication of data with a plurality of scheduled hew stations in accordance with a non-contention based scheduled orthogonal frequency division multiple access (OFDMA) technique in accordance with signaling information indicated in the hew-SIG,
wherein the scheduled OFDMA technique is one of an uplink OFDMA technique, a downlink OFDMA technique or a multi-user multiple-input multiple-output (MU-MIMO) technique.
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This application claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application Ser. No. 61/906,059 filed Nov. 19, 2013 U.S. Provisional Patent Application Ser. No. 61/973,376, filed Apr. 1, 2014, U.S. Provisional Patent Application Ser. No. 61/976,951 filed Apr. 8, 2014, U.S. Provisional Patent Application Ser. No. 61/986,256, filed Apr. 30, 2014, U.S. Provisional Patent Application Ser. No. 61/986,250, filed Apr. 30, 2014, and to U.S. Provisional Patent Application Ser. No. 61/991,730, filed May 12, 2014, each of which is incorporated herein by reference in its entirety.
Embodiments pertain to wireless networks. Some embodiments relate to Wi-Fi networks and networks operating in accordance with the IEEE 802.11 standards. Some embodiments relate to high-efficiency wireless or high-efficiency Wi-Fi (HEW) communications in accordance with the IEEE 802.11ax draft standard.
IEEE 802.11ax (High Efficiency Wi-Fi (HEW)) is the successor to IEEE 802.11ac standard and is intended to increase the efficiency of wireless local-area networks (WLANs). HEW's goal is to provide up to four-times or more the throughput of IEEE 802.11ac standard. HEW may be particularly suitable in high-density hotspot and cellular offloading scenarios with many devices competing for the wireless medium may have low to moderate data rate requirements. The Wi-Fi standards have evolved from IEEE 802.11b to IEEE 802.11g/a to IEEE 802.11n to IEEE 802.11ac and now to IEEE 802.11ax. In each evolution of these standards, there were mechanisms to afford coexistence with the previous standard. For HEW, the same requirement exists for coexistence with legacy devices and systems.
Thus there are general needs for systems and methods that that allow HEW devices to coexist with legacy devices that operate in accordance with prior versions of the standards. There are general needs for systems and methods that that allow HEW communications to be distinguished from legacy communications and provide coexistence with legacy devices and systems.
The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims.
Embodiments disclosed herein provide for coexistence of High Efficiency Wi-Fi (HEW) devices with existing legacy Wi-Fi devices. Legacy devices may refer to devices operating in accordance with previous Wi-Fi standards and/or amendments such as IEEE 802.11g/a, IEEE 802.11n or IEEE 802.11ac. HEW is a recent activity in IEEE to evolve the Wi-Fi standard. It has several target use cases, with a large focus on improving system efficiency in dense deployed networks. Since it is an evolution of the previous standards and needs to coexist with the legacy systems, a technique to identify each transmission as either a HEW packet or a legacy packet is needed. Additionally, it would be advantageous if the technique to identify the HEW transmissions could at the same time defer legacy devices. Finally, since one focus on HEW is efficiency, another aspect is to have a mechanism which accomplishes these things without adding any additional overhead to each transmission and possibly reducing the overhead.
Embodiments disclosed herein provide techniques to notify HEW devices that an HEW compliant transmission is occurring while also deferring legacy devices and doing so with little or no additional overhead from what is done in legacy transmissions and in some embodiments, less overhead. Since HEW is an evolution of the existing Wi-Fi standards, there have not been any previous solutions to address this need.
In some embodiments, the preamble portion of the packet has been increased and new fields added with various modulation formats so that the new releases could be identified. Some embodiments described herein are configured to defer legacy devices using the legacy signal field (L-SIG) and build upon the coexistence approach adopted in IEEE 802.11n and IEEE 802.11ac. In those systems, the rate field of the L-SIG was fixed to a set known value and the length was set to a length that would defer those devices beyond the transmission of an IEEE 802.11n or an IEEE 802.11ac transmission.
In some embodiments disclosed herein, the same fixed value in the rate field may be used although this is not a requirement. In some embodiments, the length field of the L-SIG may be computed differently from what is done in an IEEE 802.11n/ac system to allow deferral of legacy systems and identification of an HEW transmission. These embodiments are described in more detail below.
Following the L-SIG in an IEEE 802.11n/ac transmission are additional SIG fields. In IEEE 802.11n/ac systems, these SIG fields follow directly after the L-SIG and are phase rotated in order to allow identification. In the embodiments disclosed herein, an HEW signal field may also be used if needed and may use a modified legacy length value allowing for several preamble designs and potentially several payloads to support not only single user (SU) packets to multi-user (MU) packets like multi-user multiple-input multiple-output (MU-MIMO) or orthogonal frequency division multiple access (OFDMA). In these embodiments that use uplink MU-MIMO or uplink OFDMA, an access point (AP) may operate as a master station which would have mechanisms to contend and hold the medium. Uplink transmissions from scheduled HEW stations may immediately follow. In those cases, the AP may signal the specific devices that are targeted for uplink transmission the transmission parameters. Therefore, each device that transmits in the uplink would not need to send any additional configuration parameters and therefore does not need an additional SIG field in the preamble during their transmission.
Embodiments disclosed herein also allow legacy devices that missed the initial AP transmission (e.g., when returning from a power save mode) to detect the signal and properly defer irrespective of them being an IEEE 802.11a, an IEEE 802.11n or an IEEE 802.11ac device. In these embodiments, a new signal field modulation format is disclosed in which the first symbol is set as rotated BPSK (i.e., rotated by 90 degrees) and then the second would be BPSK (i.e., not rotated). These embodiments are described in more detail below.
Legacy stations 106 may include, for example, non-HT stations 108 (e.g., IEEE 802.11a/g stations), HT stations 110 (e.g., IEEE 802.11n stations), and VHT stations 112 (e.g., IEEE 802.11ac stations). Embodiments disclosed herein allow HEW stations 104 to distinguish transmissions (e.g., packets such as packet protocol data units (PPDUs)) from transmissions of legacy stations 106 and cause legacy stations 106 to at least defer their transmissions during HEW transmissions providing backwards compatibility. In some embodiments, the length field of the legacy signal field (L-SIG) may be used to cause some legacy stations 106 to defer transmissions. In some embodiments, the length field of the L-SIG may be used to distinguish HEW PPDUs from non-HEW PPDUs. In some embodiments, a phase rotation applied to a subsequent or additional signal field (an HT-SIG, a VHT SIG or an HEW SIG) may be used to distinguish HT PPDUs, VHT PPDUs and HEW PPDUs. In some embodiments, the rate field of the L-SIG may be used to cause some legacy stations 106 to defer transmissions and distinguish non-HT transmissions from HT, VHT and HEW transmissions. These embodiments are discussed in more detail below.
In accordance with embodiments, the master station 102 may include hardware processing circuitry including physical layer (PHY) and medium-access control layer (MAC) circuitry which may be arranged to contend for a wireless medium (e.g., during a contention period) to receive exclusive control of the medium for an HEW control period (i.e., a transmission opportunity (TXOP)). The master station 102 may transmit an HEW master-sync transmission at the beginning of the HEW control period. During the HEW control period, the HEW stations 104 may communicate with the master station 102 in accordance with a non-contention based multiple-access technique (e.g., an OFDMA technique or MU-MIMO technique). This is unlike conventional Wi-Fi communications in which devices communicate in accordance with a contention-based communication technique, rather than a non-contention multiple-access technique. During the HEW control period, legacy stations 106 refrain from communicating and defer their transmissions. In some embodiments, the HEW master-sync transmission may be referred to as an HEW control and schedule transmission.
In accordance with some embodiments, the master-sync transmission may include a multi-device HEW preamble arranged to signal and identify data fields for a plurality of scheduled HEW stations 104. The master station 102 may further be arranged to transmit (in the downlink direction) and/or receive (in the uplink direction) one or more of the data fields to/from the scheduled HEW stations 104 during the HEW control period. In these embodiments, the master station 102 may include training fields in the multi-device HEW preamble to allow each of the scheduled HEW stations 104 to perform an initial channel estimate.
In accordance with some embodiments, an HEW station 104 may be an IEEE 802.11ax configured station (STA) that is configured for HEW operation. An HEW station 104 may be configured to communicate with a master station 102 in accordance with a scheduled multiple access technique during the HEW control period and may be configured to receive and decode the multi-device HEW preamble of an HEW frame or PPDU. An HEW station 104 may also be configured to decode an indicated data field received by the master station 102 during the HEW control period. Examples of HEW PPDUs are illustrated in
In accordance with some embodiments, the master station 102 may be arranged to select a number of HEW long-training fields (LTFs) to be included in the multi-device HEW preamble of an HEW frame. The HEW frame may comprise a plurality of links for transmission of a plurality of data streams. The master station 102 may also transmit the selected number of LTFs sequentially as part of the multi-device HEW preamble. The master station 102 may also transmit/receive a plurality of data fields sequentially to/from each of a plurality of scheduled HEW stations 104. The data fields may be part of the HEW frame. Each data field may correspond to one of the links and may comprise one or more data streams. In some embodiments, the data fields may be separate packets. The master station 102 may also be arranged receive packets from HEW stations 104 in the uplink direction during the HEW control period.
In some embodiments, the selection of the number of LTFs to be included in the multi-device HEW preamble may be based on a maximum number of streams to be transmitted on a single link. In some embodiments, the selection of the number of LTFs to be included in the multi-device HEW preamble may be based on a scheduled HEW station 104 with a greatest channel estimation need (e.g., the scheduled HEW station 104 receiving the greatest number of streams on a single link). In some embodiments, the selection of the number of LTFs to be included in the multi-device HEW preamble may be based on the sum of greatest number of streams on each single link that scheduled HEW stations 104 would receive. In some embodiments, the number of LTFs to be included in the multi-device HEW preamble may be predetermined. In these embodiments, the number of LTFs to be included in the multi-device HEW preamble may be based on the maximum number of streams that can be transmitted on a single link.
In some embodiments, the master station 102 may be arranged to configure the multi-device HEW preamble include an HEW control signal field (i.e., HEW SIG-B) to identify and signal each of the data fields of the HEW frame. In these embodiments, a single HEW preamble is included in an HEW frame, which is unlike conventional techniques which include a preamble for each link.
IEEE 802.11ac devices are also able to discern IEEE 802.11ac packets from other legacy (IEEE 802.11a/g and IEEE 802.11n) packets. In the discussion above regarding IEEE 802.11n, the HT-SIG field 212 (
In some embodiments, the L-SIG 206 may be configured to include at least a length field and a rate field. The master station 102 may select a value for the length field that is non-divisible by three for communicating with the HEW stations 104 and may select a value for the length field that is divisible by three for communicating with at least some legacy stations 106. In these embodiments, when the length field is not divisible by three, at least some legacy stations 106 (i.e., HT stations 110 and VHT stations 112) would determine that the length field value in the L-SIG 206 is invalid and will properly defer their transmissions. When the length field is not divisible by three, HEW stations 104 may be configured to identify the PPDU as an HEW PPDU and decode one or more of the fields that follow the L-SIG 206.
In some embodiments, the master station 102 is further arranged to configure the L-SIG 206 with a valid parity bit (i.e., the L-SIG parity bit) when the length field is selected to be divisible by three and when the length field is selected to be non-divisible by three. In these embodiments, the L-SIG may always be configured with a valid parity bit. In these embodiments, when a valid L-SIG parity bit is indicated, the physical layer (PHY) of a device may maintain a busy indication for the predicted duration of the PPDU. Thus legacy stations 106 will defer for the value indicated by the length (L_LENGTH) field in the L-SIG 206 even if the value is invalid (i.e., not divisible by three) as long as the parity bit is valid.
In some embodiments, the master station 102 may multiply a ceiling function by three and subtract either two or one to calculate the value for the length field for the HEW PPDUs. By multiplying the ceiling function by three and then subtracting two or one assures that the length field is not divisible by three. The master station 102 may multiply the ceiling function by three and subtract three to calculate the value for the length field for HT and VHT PPDUs. By multiplying the ceiling function by three and then subtracting three assures that the length field is divisible by three. These embodiments are discussed in more detail below.
In some embodiments, the length calculation used to populate the L-SIG for 0.11ac packets is give as (L_LENGTH):
In the above equations, the T variable is the time for the respective portions of the packet and variables TSYMS, TSYM and NSYM represent the short GI symbol interval, symbol interval and number of symbols in a packet respectively. The equation in the L_LENGTH calculation uses a ceiling function multiplied by three and then three is subtracted. For any value of TXTIME, the L_LENGTH will be divisible by three. Thus, for HEW packets, embodiments disclosed herein may set the L_LENGTH to a value that is not divisible by three. In some embodiments, the expression for L_LENGTH for HEW packets may be:
This would result in a length that is one larger than before but is not divisible by three. Doing this may be sufficient to identify HEW packets and may allow coexistence with legacy (IEEE 802.11a/g/n/ac) devices. Legacy stations 106 would decode the L-SIG, and defer for a time based on the L_LENGTH value regardless of the value.
In these embodiments, no additional signaling or other metrics need to be added in order to identify HEW packets. That is very appealing in HEW where efficiency is a key design parameter. Additionally, for techniques like uplink MU-MIMO and OFDMA to be efficient a very short preamble is desirable. These embodiments are very efficient with no overhead and provide full coexistence with legacy systems.
In some embodiments, the master station 102 may be arranged to configure the PPDU to include a subsequent/additional signal field 210 (e.g., HT-SIG 212, VHT-SIG 222, or HEW-SIG 232) following the L-SIG 206. The subsequent signal field 210 may have first and second symbols that are BPSK modulated. In these embodiments, the master station 102 may select a phase rotation for application to the BPSK modulation of at least one of the first and second symbols of the subsequent signal field 210 to distinguish a HT PPDU (
In some embodiments, for communicating with HEW stations 104, the master station 102 may configure the PPDU to include a number of long-training fields (LTFs) 234 to be included in a multi-device HEW preamble the PPDU. The number of LTFs 234 may be based on a maximum number of streams communicated over a link. The master station 102 may contend for a wireless medium during a contention period to receive control of the medium for an HEW control period (i.e., a TXOP) and may transmit the PPDU during the HEW control period. During the HEW control period, the master station 102 may operate as a master station having exclusive use of the wireless medium for communication of data with a plurality of scheduled HEW stations 104 in accordance with a non-contention based scheduled OFDMA technique in accordance with signaling information indicated in an HEW signal field. The scheduled OFDMA technique may, for example, be an uplink (UL) OFDMA technique, a downlink (DL) OFDMA technique or an UL or DL multi-user multiple-input multiple-output (MU-MIMO) technique.
In some embodiments, for an HEW PPDU, each data field may be associated with either a single user (SU) link or a multi-user (MU) link and each link may be configurable to provide multiple streams of data. The links of the HEW PPDU may be configurable to have a bandwidth of one of 20 MHz, 40 MHz, 80 MHz or 160 MHz.
In accordance with embodiments, for communicating with the HEW stations 104, the subsequent signal field 210 may be an HEW signal field (HEW-SIG) 232 (
For communicating with VHT stations 112, the subsequent signal field 210 may be an VHT signal field (VHT-SIG) 222 (
For communicating with HT stations 110, the subsequent signal field 210 may be an HT signal field (HT-SIG) 212 (
For communicating with non-HT stations 108, the access point may refrain from including the subsequent signal field 210 following the L-SIG 206. The data field 208 of a non-HT PPDU may have conventional (non-phase rotated) modulation (e.g., BPSK to 64QAM) applied for all symbols allowing a non-HT PPDU to be identified and distinguished from other HT, VHT and HEW PPDUs.
In accordance with some embodiments, the phase rotation of the symbols in the subsequent signal field 210 may be used to distinguish an HEW PPDU from a non-HEW PPDU, such as a HT PPDU or a VHT PPDU. In these embodiments, it may not be necessary to use the length field of the L-SIG 206 to distinguish an HEW PPDU from a non-HEW PPDU and the length field may be set to a value that is divisible by three, although the scope of the embodiments is not limited in this respect. In some embodiments, the length field may also be used to distinguish an HEW PPDU from a non-HEW PPDU, such as a HT PPDU or a VHT PPDU.
In some embodiments, for communicating with the HEW stations 104 and some legacy stations 106 including HT stations 110 and VHT stations 112, the master station 102 may select a value for the rate field to cause the non-HT stations 108 to defer transmissions. In these embodiments, the non-HT stations 108 may correctly decode the L-SIG 206 but may be unable to correctly decode the remainder of the PPDU based on the indicated rate (or the cyclic-redundancy check (CRC) may fail) causing these stations to ignore the PPDU but defer based on the length indicated in the length field of the L-SIG 206. In these embodiments, a predetermined value (e.g., 5 or 6) may be selected for the rate field which may cause the non-HT stations 108 to defer their transmissions because of their inability to decode the subsequent fields.
In operation 402, a PPDU is configured to include one or more legacy training fields and a legacy signal field (L-SIG) 206 following the legacy training fields.
In operation 404, the L-SIG 206 is configured to include at least a length field.
In operation 406, a value for the length field that is not divisible by three is selected for communicating with the HEW stations 104.
In operation 408, a value for the length field that is divisible by three is selected for communicating with at least some legacy stations 106.
In operation 410, the PPDU is configured to include an additional signal field following the L-SIG 206.
In operation 412, a phase rotation is selected for application to the BPSK modulation of at least one of the first and second symbols of the additional signal field to distinguish a HT PPDU, a VHT PPDU and an HEW PPDU.
In some embodiments, operation 412 may be optional as the value selected for the length field in operations 406 and 408 may be used to distinguish HEW from non-HEW PPDUs. In some alternate embodiments, the value for the length field that is divisible by three is selected for communicating with all stations and the phase rotation of the symbols of the additional signal field may be used to distinguish a HT PPDU, a VHT PPDU and an HEW PPDU.
In accordance with some embodiments, when operating as an HEW station 104, the HEW device 500 may be arranged to distinguish an HEW PPDU from a non-HEW PPDU based at least in part on a value in a length field in the L-SIG 206 (
In some embodiments, when operating as an HEW station 104, the HEW device 500 may be arranged to distinguish an HEW PPDU from a non-HEW PPDU based on the phase rotation of symbols of a subsequent signal field. In these embodiments, the HEW device 500 may be configured to receive an L-SIG 206 and receive a subsequent signal field 210 (HT-SIG 212, VHT-SIG 222, or HEW-SIG 232). The subsequent signal field 210 may have first and second symbols that are BPSK modulated. In these embodiments, the HEW device 500 may determine whether the PPDU is a HT PPDU, a VHT PPDU or an HEW PPDU based on the phase rotation applied to the BPSK modulation of at least one of the first and second symbols of the subsequent signal field 210. For an HEW PPDU, a ninety-degree phase rotation may have been applied to the BPSK modulation of the first symbol 332A and no phase rotation would have been applied to the BPSK modulation of the second symbol 332B of the subsequent signal field 210.
In accordance with some embodiments, the MAC 504 may be arranged to contend for a wireless medium during a contention period to receive control of the medium for the HEW control period and configure an HEW PPDU (e.g.,
In some embodiments, the HEW device 500 may be configured to communicate using OFDM communication signals over a multicarrier communication channel. In some embodiments, HEW device 500 may be configured to communicate in accordance with one or more specific communication standards, such as the Institute of Electrical and Electronics Engineers (IEEE) standards including IEEE 802.11-2012, 802.11n-2009, 802.11ac-2013, 802.11ax standards and/or proposed specifications for WLANs, although the scope of the invention is not limited in this respect as they may also be suitable to transmit and/or receive communications in accordance with other techniques and standards.
In some embodiments, the HEW device 500 may be part of a portable wireless communication device, such as a personal digital assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone or smartphone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), or other device that may receive and/or transmit information wirelessly. In some embodiments, the HEW device 500 may include one or more of a keyboard, a display, a non-volatile memory port, multiple antennas, a graphics processor, an application processor, speakers, and other mobile device elements. The display may be an LCD screen including a touch screen.
The antennas of the HEW device 500 may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some MIMO embodiments, the antennas may be effectively separated to take advantage of spatial diversity and the different channel characteristics that may result between each of antennas and the antennas of a transmitting station.
Although the HEW device 500 is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements of the HEW device 500 may refer to one or more processes operating on one or more processing elements.
Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer-readable storage device, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable storage device may include any non-transitory mechanism for storing information in a form readable by a machine (e.g., a computer). For example, a computer-readable storage device may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and other storage devices and media. Some embodiments may include one or more processors and may be configured with instructions stored on a computer-readable storage device.
The Abstract is provided to comply with 37 C.F.R. Section 1.72(b) requiring an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.
Perahia, Eldad, Kenney, Thomas J., Azizi, Shahrnaz
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