HK1115952A - Method and apparatus for generating loud packets to estimate path loss - Google Patents

Description

Method and apparatus for generating loud packets to estimate path loss

Technical Field

The present invention relates to a wireless communication system, such as a Wireless Local Area Network (WLAN), including a plurality of wireless transmit/receive units (WTRUs), i.e., mobile stations. More particularly, the present invention relates to a method and apparatus for generating loud packets to estimate path loss between WTRUs.

Background

In a wireless system in which the multiple access scheme is based on carrier sense access/collision avoidance (CSMA/CA) according to the IEEE 802 standard (e.g., IEEE 802.11), WTRUs determine when to attempt to receive and transmit packets based on the strength of signals received from neighboring WTRUs that use the same channel. By avoiding simultaneous transmissions, multiple WTRUs can avoid interference when sharing the same channel.

Key parameters, such as the Energy Detection Threshold (EDT) and the Delay Threshold (DT), are typically used by the WTRU to determine when it can transmit or receive a packet, EDT being the minimum received signal power at which it attempts to receive a packet and DT being the minimum received signal power at which the WTRU will delay transmitting a packet, and DT may or may not be the same as EDT.

Although the underlying concept of CSMA/CA is well established, there are situations that result in excessive capacity reduction relative to maximum capacity, for example, two transmitters (communicating with different receivers) can transmit simultaneously without significant mutual interference, but they do not transmit because they listen to each other at values higher than the individual EDT and/or DT, which would result in wasted capacity that could be avoided if any of the following actions were to occur:

a) the WTRUs decrease their transmission power so that the WTRUs are unable to listen to each other beyond the EDT and/or DT but still communicate with their respective counterparts at an optimal data rate;

b) the WTRUs increase their EDT and/or DT such that signals received from the other party are below their threshold; or is

c) Combining a) and b).

This technique of determining and setting the above parameters (transmission power, EDT, DT) by a node or system will be referred to as deferred management hereinafter. If WTRUs know the path loss between each other and the EDT or DT values used by other WTRUs, it may be helpful to set these parameters appropriately so that the WTRUs (or other nodes, such as Access Points (APs) that control certain parameters of the WTRUs) can predict whether transmission at a particular level will result in received signals that are above or below the EDT value of a given neighboring WTRU, which information may then be used in algorithms that help optimize capacity.

The obtained path loss estimate can also be used in positioning. The location of the WTRU is estimated using the path loss settings between pairs of WTRUs and the location of a number of fixed WTRUs (typically APs) or mesh points (MPs in a mesh network). This estimation may be performed by a node (which may or may not be a WTRU) that collects path loss estimates from one or more different WTRUs.

Therefore, a method is needed by which a WTRU can reliably estimate its path loss to other WTRUs.

Problems to be solved

An explicit way to estimate the path loss between a first WTRU and a second WTRU adjacent to the first WTRU is to subtract the received power sensed by the transmit power used by the second WTRU from the first WTRU, assuming that the first WTRU can determine the signal power measured by the second WTRU transmitting the first WTRU, the following are factors that cannot be achieved in the current state of the art of WTRUs:

1) in the context of transmit power settings for APs, WTRUs and MPs in this area, WLANs are the owner and are not communicating with other WTRUs, for example, existing 802.11h/802.11k Transmit Power Control (TPC) mechanisms only force the maximum transmit power setting for the Basic Service Set (BSS) and they cannot exceed this value for regulatory purposes. It should be appreciated that any WTRU may vary the transmit power at the maximum of the mandatory limit without communicating with its internal owner to determine the transmit power to other WTRUs, APs or MPs.

2) The transmit power used per WTRU may vary on a packet basis. This means that in order for a first WTRU to estimate the path loss of a second WTRU separate from it, the first WTRU needs to receive a packet from the second WTRU, whereby the power at which the packet is transmitted will be indicated within the packet. In the above example, signaling allowing transmission of packets such as this is only the 802.11h/802.11k TPC request/TPC report frame exchange mechanism, which requires a dedicated bidirectional signaling exchange and cannot be set periodically. In addition, the TPC request/report cannot be sent to WTRUs located outside the BSS. In situations where WTRUs aim to adjust their transmit power and DT/EDT parameters so that they can increase the capacity of the system without creating a hidden node in the BSSs of the system, it is necessary to obtain path losses between WTRUs from a different WTRU.

3) In many cases, the first WTRU may not hear the second WTRU because the second WTRU is transmitting at a lower power than maximum power, which may occur if the second WTRU uses battery management techniques or defers management techniques. In the case where a WTRU aims to adjust its deferral management parameters, it is noted that it may be desirable to estimate path losses for WTRUs even if they cannot listen to them. There is no way today for one WTRU node to order another WLAN node to increase its transmission power or even directly manage the use of a particular transmission power, rather than using the specified maximum power. This may also apply to the TPC request/TPC report mentioned earlier.

The above-mentioned problems with mechanisms (or lack thereof) may indicate that path loss estimation between WTRUs does cause problems, which in some instances forces WTRUs to assume the transmit power level of a neighboring WTRU, which is not very accurate under different WTRU manufacturers, and may be possible for neighboring WTRUs to use lower than maximum transmit power. In other examples, the mechanism may completely prevent path estimation between two WTRUs from occurring.

Disclosure of Invention

The present invention is implemented in a wireless communication system, such as a WLAN, that includes a plurality of WTRus and a coordinating node, such as an Access Point (AP). Transmitting, by a first one of the WTRUs, a loud packet to a second one of the WTRUs. The coordinating node transmits a loud packet generation request message. A first of the WTRUs receives the loud packet generation request message and transmits at least one loud packet at a transmission power specified by the loud packet generation request message. Optionally, the first WTRU transmits a loud packet generation response message. A second one of the WTRUs receives the loud packet and determines a path loss between the first WTRU and the second WTRU determined by subtracting the signal strength of the loud packet from the determined transmission power of the loud packet.

Drawings

The invention will be understood in more detail from the following description of a preferred embodiment, given as an example, and with reference to the accompanying drawings, in which:

FIG. 1 is a signal flow diagram in which loud packets are sent from a coordinating node to one or more WTRUs in a wireless communication system configured in accordance with the present invention;

FIG. 2 is a block diagram of a wireless communication system including a plurality of WTRUs using a smart antenna for transmitting and receiving loud packets in accordance with the present invention;

FIG. 3 is a flowchart of a process for estimating path loss between two WTRUs, in accordance with one embodiment of the present invention; and

FIG. 4 is a flowchart of a process for estimating path loss between two WTRUs based on information contained in a loud packet generation request message transmitted by a coordinating node, in accordance with another embodiment of the present invention; and

figure 5 is a flowchart of a process for estimating path loss between two WTRUs based on a status specified by a loud packet generation request message transmitted by a third WTRU in accordance with yet another embodiment of the present invention.

Detailed Description

When referred to hereafter, a "WTRU" includes, but is not limited to, a User Equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, or any other device capable of operating in a wireless environment. When referred to hereafter, an Access Point (AP) includes, but is not limited to, a node B, site controller, base station, or any other interfacing device in a wireless communication environment.

Hereinafter, a WTRU may be considered any node in a wireless communication system (e.g., an IEEE 802 WLAN system), a station (AP or non-AP), an Independent Basic Service Set (IBSS) or a basic structure Basic Service Set (BSS), or a mesh point, mesh AP or mesh portal in a mesh network.

The features of the present invention may be integrated within an Integrated Circuit (IC) or may be provided in a circuit comprising a multitude of interconnecting components.

Concept of loud encapsulation

In accordance with one embodiment of the present invention, WTRUs transmit packets at a high transmission power in time, (hereinafter referred to as "loud packets"), whereby the packet transmission power level is known to other WTRUs. These loud packets need not be sent to any particular WTRU or group of WTRUs, but may simply be broadcast to a group of WTRUs receiving on the same frequency channel. A neighboring WTRU that needs to calculate an estimate of the path loss for the WTRU transmitting the loud packet can be easily known by comparing the received signal strength of the loud packet to the transmission power indicated or known by the loud packet. For example, the path loss estimate may be obtained by using the following procedure:

signal strength (dBm) side procedure (1) for loud packets received with path loss (dB) equal to the transmission power (dBm) of the loud packet

Preferably, the transmission power of the loud packet is indicated in an information field within the loud packet. Alternatively, the transmit power may be broadcast periodically by the AP, indicating to each WTRU immediately after connection with the AP, or as part of other signaling exchanges to the WTRU. In this case, there is a message field at the loud packet to inform the receiving WTRU that it is a loud packet and not a normal packet. Preferably, the transmit power of the loud packet should be equal to the maximum transmit power of the WTRU transmitting the loud packet, which ensures the maximum possible range of successful reception of the loud packet and the most reliable estimate, however, this is not necessary. It is noted that other packets than loud packets may be transmitted at a lower power to balance the parameters of other systems.

An identifier (e.g., MAC address) of the WTRU transmitting the loud packet should also be included in the message field so that the receiving WTRUs know which WTRU the path loss corresponds to.

Alternatively, loud packets may be implemented by any existing signaling frame that is transmitted at a transmission power selected by the transmitter and known to the receiver. For example, the transmission power may be known by the receiver via an Information Element (IE) appended to or carried in an existing signaling frame. Alternatively, the loud packet known transmission power may be known by the receiver as part of a prior handshake with the sender of the loud packet.

Advantageously, beacon/probe response frames are used as loud packets, the individual transmission power of which may be the beacon/probe request frame itself, or a pre-agreed transmission power setting for these frames, which are communicated to the WTRUs by other means, such as proximity signaling.

Additional information reported in loud packets

Loud packets may be used as a flexible reporting mechanism to help receiving WTRUs optimize their parameters (transmit power, EDT, DT), which may be reported by the transmitting WTRU (sender) (except for the WTRU identifier and the known transmit power of the loud packet, or as a standalone signal if desired):

1) in a basic-structure BSS, the AP is connected to the WTRU's address or identifier (and/or the BSS, IBSS, or mesh identifier).

2) Power of packets used to transmit non-loud packets.

3) Path loss estimation tables are known to the sender for other WTRUs.

4) The sender receives a table of packet signal strengths (or average signal strengths) (one value per WTRU) from other WTRUs.

5) The sender receives the total duration schedule of packets (one value per WTRU) from other WTRUs in a certain amount of time.

6) Used by the sender or known by the sender as EDTs for other WTRUs.

7) Used by the sender or known by the sender regarding Channel Clear Assessment (CCA) of other WTRUs.

8) Used by the sender to transmit a packet or known by the sender to the DTs of other WTRUs.

Loading selection

To limit the amount of signaling bandwidth it uses, a loud packet may be piggybacked onto other types of packets (including flow control or management information). In this case, preferably the entire packet should be transmitted at the power of the loud packet.

Coordinated management of loud packet transmissions

The transmission of loud packets need not be restricted to certain WTRUs, however, it may be desirable to have the transmission be controlled in certain extensions by a coordinating node. Typically, the AP should play the role of coordinating nodes in an infrastructure BSS. Controlling the generation of loud packets by a coordinating node has the advantage of ensuring minimal performance, depending on the particular deferral management technique or location technique used in the system.

Fig. 1 shows a signal flow diagram in which the loud packet is transmitted by a coordinating node 105 to one or more WTRUs 1101 and 110N in a wireless communication system 100, which are configured in accordance with the present invention. The management of loud packet transmissions may be accomplished by the coordinating node 105 (e.g., an AP) signaling one or more WTRUs 110 that desire to transmit loud packets. Such signaling may be performed by first transmitting a loud packet generation request message 115 from the coordinating node 105 to the wtru(s) 110. The loud packet generation request message 115 may then be broadcast to all WTRUs 110 (e.g., all WTRUs of the BSS) under the control of the coordinating node 105, or may be a unicast message. The loud packet generation request message 115 may also be added, for example, to an existing IEEE 802 signaling exchange, such as in frames associated with association/authentication or admission control procedures.

The information contained in the loud packet generation request message 115 indicates one or more of the following:

1) the transmission power for the loud packet.

2) The information to be reported in the loud packet (in all possible fields listed above).

3) There are several options for the timing of the transmission of one or more loud packets, including but not limited to:

i) periodically or semi-periodically, for a certain period between successive transmissions of loud packets.

ii) a particular number of time sequences within a particular time window (e.g.: one), the two parts are combined.

iii) after a certain condition (trigger) is met, for example:

a) packet detection by a new WTRU: or is

b) The number of packet retransmissions exceeds a certain threshold for a certain period of time.

4) The number of retransmissions of a received packet over a particular period of time exceeds a particular threshold.

5) Indicating whether the loud packet should be piggybacked (or not) on other packets.

6) Information about loud packets generated by other WTRUs (i.e.: all WTRUs mentioned above except for the non-receiving WTRU).

The wtru(s) receiving the loud packet generation request message 115 may optionally respond to a loud packet generation response message 120, as shown in fig. 1. The loud packet generation response message may indicate the transmit power that the WTRU will use to transmit the loud packet (if not specified in the request message or if different from the request), which may be useful if the transmit power of the loud packet is not indicated in the loud packet. In one embodiment, a loud packet generation request may be indicated in a field of a loud packet, and thus, the loud packet generation request message may be used by a WTRU to estimate its path loss to other WTRUs.

Uncoordinated management of loud packet transmissions

Another way in which the above-described coordination management may differ is that WTRUs may autonomously determine when to transmit loud packets and what information must be reported therein. This behavior may be pre-agreed upon by WTRUs that comply with a particular standard.

Alternatively, this mechanism may be better suited for peer-to-peer and mesh systems, allowing any WTRU (not just the coordinating node) to send a loud packet generation request message to other WTRUs.

Supporting smart antennas

The above is applicable to WTRUs that use simple antennas, and in order to support WTRUs equipped with smart antennas (i.e., multiple beam or switched beam antennas), it is useful to include some additional information in the loud packet:

1) the antenna beam used by the WTRU that wants to transmit the loud packet, (which may be specified in the loud packet generation request message of the coordinating node). Path loss between a first WTRU and a second WTRU depends on the antenna beam used, and if the WTRU transmitting the loud packet may use a different antenna beam, the receiving WTRU should know which antenna beam was used to transmit the loud packet so that it knows which antenna beam the path loss measurement is associated with.

2) An antenna beam used by a WTRU that is to transmit packets other than loud packets. The high-level deferral management algorithms must know this information in order to properly set parameters (e.g., deferral thresholds) of the receiving WTRUs.

3) The antenna beam used by the WTRU to receive the packet. This is the antenna beam used by the WTRU transmitting the loud packet to receive rather than the WTRU receiving the loud packet, so the WTRU transmitting the loud packet informs other WTRUs that whenever it receives a packet, it may use a particular antenna beam that is different from the antenna beam currently used to transmit the loud packet. This information is useful for other WTRUs, so that they can know whether a retransmission at a particular power will cause a delay at the WTRU.

Fig. 2 is a block diagram of a wireless communication system 200 including a plurality of WTRUs 2051, 2052 that transmit and receive, respectively, loud packets using smart antennas 222, 242, in accordance with the present invention. The WTRU 2051 includes a processor 210, a transmitter 215, and a receiver 220, and the WTRU 2052 includes a processor 225, a transmitter 230, and a receiver 235.

The processors 210 and 225 of the WTRUs 205 are configured to generate loud packets, loud packet generation request messages 115, and optionally loud packet generation response messages 120, which are transmitted via the transmitters 215 and 230, and the smart antennas 222, 242, respectively. Additionally, each of the receivers 220, 235 of the WTRUs 205 is configured to receive loud packets, loud packet generation request messages 115, and optionally loud packet generation response messages 120, which are received via the smart antennas 222, 242 and then processed by the processors 210, 225.

By using the loud packet information, the WTRU 205 receiving the loud packet determines the path loss for the WTRUs 205 to transmit and receive the loud packet using each of the antenna beams of the smart antennas 222, 242. It should be understood that "path loss" includes gain due to the transmit/receive antenna, and that different beams are used to receive and transmit different loud packets.

Fig. 3 is a flow chart of a process 300 for estimating path loss between two WTRUs in accordance with an embodiment of the present invention. The process 300 is implemented in a wireless communication system, such as the system 200 of figure 2, which includes a plurality of WTRUs 2051 and WTRUs 2052. A first WTRU 2051 transmits a loud packet (step 305). A second WTRU 2052 receives the loud packet (step 310), determines the signal strength (dB) of the received loud packet (step 315), and determines the transmit power (dB) of the received loud packet (e.g., obtained by the transmit power from the loud packet itself, or by a request from a loud packet generation message indicating what transmit power should be used) (step 320). The WTRU 2052 determines the path loss between the WTRU 2051 and the WTRU 2052 by subtracting the signal strength determined in step 315 from the transmit power determined in step 320 (step 325).

Fig. 4 is a flow diagram of a process 400 for estimating path loss between two WTRUs based on information contained in a loud packet generation request message transmitted by a coordinating node, in accordance with another embodiment of the present invention. The process 400 is implemented in a wireless communication system, such as the system 100 of fig. 1, which includes a coordinating node 105 and a plurality of WTRUs 1101 and 110N. The coordinating node 150 transmits a loud packet generation request message (step 405). A first one of the WTRUs 110 receives the loud packet generation request message (step 410). In an optional step 415, the first WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message. In step 420, the first WTRU transmits at least one loud packet including information specific to the loud packet generation request message. In step 425, a second one of the WTRUs 110 receives the at least one loud packet and determines a signal strength (dB) of the received loud packet (step 430), and determines a transmission power (dB) of the received loud packet based on information contained in the loud packet (step 435). In step 440, the second WTRU determines the path loss between the first WTRU and the second WTRU by subtracting the signal strength determined in step 430 from the transmit power determined in step 435.

Figure 5 is a flow diagram of a process 500 for estimating path loss between two WTRUs based on a state specified by a loud packet generation request message transmitted by a third WTRU in accordance with yet another embodiment of the present invention. A first WTRU of the plurality of WTRUs transmits a loud packet generation request message (step 505). A second one of the WTRUs receives the loud packet generation request message (step 510). In an optional step 515, the second WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message. In step 520, the second WTRU transmits at least one loud packet (e.g., at a particular transmit power, at a particular time, using a particular antenna beam of a smart antenna, etc.) based on the status specified by the loud packet generation request message. In step 525, a third one of the WTRUs receives the at least one loud packet, determines a transmission power (dB) of the received loud packet (step 535). In step 540, the third WTRU determines the path loss between the second WTRU and the third WTRU by subtracting the signal strength determined in step 530 from the transmit power determined in step 535.

In conventional wireless communication systems, path loss estimation to neighboring WTRUs is limited by a significant uncertainty factor due to the lack of information regarding the transmit power of the neighboring WTRU. The problem of allowing a WTRU to know the outgoing power of a given packet, which the sender of the TCP request/report needs to signal exclusively bi-directionally and cannot be set periodically, has been solved by indicating the transmission power in loud packets or otherwise.

In addition, in conventional wireless communication systems, if WTRUs transmit at a power far below the maximum transmission level, other WTRUs in a wide area cannot listen, which also makes path loss estimation impractical. It should be noted that in the case where the WTRU helps adjust its deferral parameter, the WTRU needs to estimate its path loss with neighboring WTRUs even though the WTRU is unable to listen at the current transmit power. The present invention also solves this problem.

In addition, in conventional wireless communication systems, a WTRU cannot correctly estimate path loss with neighboring WTRUs without WTRUs participating in the same BSS. The present invention provides a solution to this problem by controlling the WTRUs to generate loud packets.

Finally, path loss estimation for smart antenna equipped WTRUs is not supported in existing wireless communication systems, and the present invention supports intra-WTRU path loss estimation when WTRUs are equipped with smart antennas.

Examples

1. In a wireless communication system including a plurality of wireless transmit/receive units (WTRUs), a method of estimating path loss, the method comprising:

a first one of the WTRUs transmitting a loud packet;

receiving the loud packet by a second one of the WTRUs;

the second WTRU determining a signal strength of the received loud packet;

the second WTRU determining a transmit power of the received loud packet; and

the second WTRU determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmit power.

2. The method of embodiment 1 wherein the transmission power is indicated in an information field included in the loud packet.

3. The method of embodiment 1 wherein the wireless communication system further comprises an Access Point (AP) and the transmit power is periodically broadcast by an Access Point (AP) including a field with the first WTRU's maximum transmit power.

4. The method of embodiment 1 wherein the wireless communication system further comprises an Access Point (AP) and the second WTRU is instructed on the transmit power immediately after the second WTRU is associated with the AP.

5. The method of embodiment 1 wherein the loud packet includes an information field indicating the maximum transmit power of the first WTRU.

6. The method of embodiment 1 wherein the loud packet includes an information field including an identifier indicating the first WTRU.

7. The method of embodiment 6 wherein the identifier is a Media Access Control (MAC) address.

8. The method of embodiment 1 wherein the loud packet comprises an IEEE 802.11 signaling frame.

9. The method of embodiment 1, further comprising:

the loud packet is piggybacked onto other types of packets.

10. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs) and a coordinating node, the method comprising:

the coordinating node transmits a loud packet generation request message;

a first one of the WTRUs receiving the loud packet generation request message;

the first WTRU transmitting at least one loud packet at a transmission power specified by the loud packet generation request message;

a second one of the WTRUs receiving the at least one loud packet;

the second WTRU determining a signal strength of the received loud packet;

the second WTRU determining a transmit power of the received loud packet; and

the second WTRU determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmit power.

11. The method of embodiment 10 wherein the coordinating node is an Access Point (AP).

12. The method of embodiment 10, further comprising:

the first WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

13. The method of embodiment 12 wherein the loud packet generation response message indicates the transmission power that the first WTRU will use to transmit the loud packet.

14. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs) and a coordinating node, the method comprising:

the coordinating node transmits a loud packet generation request message;

a first one of the WTRUs receiving the loud packet generation request message;

the first WTRU transmitting at least one loud packet including a message specified by the loud packet generation request message;

a second one of the WTRUs receiving the at least one loud packet;

the second WTRU determining a signal strength of the received loud packet;

the second WTRU determining a transmit power of the received loud packet based on the information contained in the loud packet; and

the second WTRU determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmit power.

15. The method of embodiment 14 wherein the coordinating node is an Access Point (AP).

16. The method of embodiment 14, further comprising:

the first WTRU generates response information in response to the loud packet generation request information by transmitting a loud packet.

17. The method of embodiment 16 wherein the loud packet generation response message indicates the transmission power that the first WTRU will use to transmit the loud packet.

18. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs) and a coordinating node, the method comprising:

the coordinating node transmits a loud packet generation request message;

a first one of the WTRUs receiving the loud packet generation request message;

the first WTRU transmitting at least one loud packet at a time specified by the loud packet generation request message;

a second one of the WTRUs receiving the at least one loud packet;

the second WTRU determining a signal strength of the received loud packet;

the second WTRU determining a transmit power of the received loud packet; and

the second WTRU determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmit power.

19. The method of embodiment 18 wherein the coordinating node is an Access Point (AP).

20. The method of embodiment 18, further comprising:

the first WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

21. The method of embodiment 20 wherein the loud packet generation response message indicates the transmission power that the first WTRU will use to transmit the loud packet.

22. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs), the method comprising:

a first one of the WTRUs transmitting a loud packet generation request message;

a second one of the WTRUs receiving the loud packet generation request message;

the second WTRU transmitting at least one loud packet at a transmission power specified by the loud packet generation request message;

a third one of the WTRUs receiving the at least one loud packet;

the third WTRU determining a signal strength of the received loud packet;

the third WTRU determining a transmit power of the received loud packet; and

the third WTRU determining a path loss between the second WTRU and the third WTRU by subtracting the determined signal strength from the determined transmit power.

23. The method of embodiment 22, further comprising:

the second WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

24. The method of embodiment 23 wherein the loud packet generation response message indicates the transmission power that the second WTRU will use to transmit the loud packet.

25. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs), the method comprising:

a first one of the WTRUs transmitting a loud packet generation request message;

a second one of the WTRUs receiving the loud packet generation request message;

the second WTRU transmitting at least one loud packet including a message specified by the loud packet generation request message;

a third one of the WTRUs receiving the at least one loud packet;

the third WTRU determining a signal strength of the received loud packet;

the third WTRU determining a transmit power of the received loud packet based on the information contained in the loud packet; and

the third WTRU determining a path loss between the second WTRU and the third WTRU by subtracting the determined signal strength from the determined transmit power.

26. The method of embodiment 25, comprising:

the second WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

27. The method of embodiment 26 wherein the loud packet generation response message indicates the transmission power that the second WTRU will use to transmit the loud packet.

28. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs), comprising:

a first one of the WTRUs transmitting a loud packet generation request message;

a second one of the WTRUs receiving the loud packet generation request message;

the second WTRU transmitting at least one loud packet at a time specified by the loud packet generation request message;

a third one of the WTRUs receiving the at least one loud packet;

the third WTRU determining a signal strength of the received loud packet;

the third WTRU determining a transmit power of the received loud packet; and

the third WTRU determining a path loss between the second WTRU and the third WTRU by subtracting the determined signal strength from the determined transmit power.

29. The method of embodiment 28, further comprising the steps of:

the second WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

30. The method of embodiment 29 wherein the loud packet generation response message indicates the transmission power that the second WTRU will use to transmit the loud packet.

31. In a wireless communication system including a plurality of wireless transmit/receive units (WTRUs), each WTRU including a smart antenna, a method of coordinating the management of loud packets used to estimate path loss, comprising:

a first of the WTRUs receiving a loud packet generation request message that specifies a particular antenna beam of the smart antenna for transmitting the loud packet;

the first WTRU transmitting at least one loud packet using the particular antenna beam specified by the loud packet generation request message;

a second one of the WTRUs receiving the at least one loud packet;

the second WTRU determining a signal strength of the received loud packet;

the second WTRU determining a transmit power of the received loud packet; and

the second WTRU determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmit power.

32. The method of embodiment 31, further comprising:

the second WTRU determines a path loss for each antenna beam of the smart antenna for receiving loud packets.

33. The method of embodiment 31, further comprising:

the first WTRU determines a path loss for each antenna beam of a smart antenna used to transmit the loud packet.

34. A wireless communication system that coordinates loud packet management for estimating path loss, comprising:

a coordinating node; and

a plurality of wireless transmit/receive units (WTRUs), wherein the coordinating node transmits a loud packet generation request message, a first WTRU of the WTRUs receives the loud packet generation request message and transmits at least one loud packet at a transmission power specified by the loud packet generation request message, and a second WTRU of the WTRUs receives the at least one loud packet, determines a signal strength of the received loud packet, determines a transmission power of the received loud packet, and determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmission power.

35. The system of embodiment 34 wherein the coordinating node is an Access Point (AP).

36. The system of embodiment 34 wherein the first WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

37. The system of embodiment 36 wherein the loud packet generation response message indicates the transmission power that the first WTRU will use to transmit the loud packet.

38. A wireless communication system that coordinates loud packet management for estimating path loss, comprising:

a coordinating node; and

a plurality of wireless transmit/receive units (WTRUs), wherein the coordinating node transmits a loud packet generation request message, a first WTRU of the WTRUs receives the loud packet generation request message and transmits at least one loud packet at a time specified by the loud packet generation request message, and a second WTRU of the WTRUs receives the at least one loud packet, determines a signal strength of the received loud packet, determines a transmission power of the received loud packet, and determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmission power.

39. The system of embodiment 38 wherein the coordinating node is an Access Point (AP).

40. The system of embodiment 38 wherein the first WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

41. The system of embodiment 40 wherein the loud packet generation response message indicates the transmission power that the first WTRU will use to transmit the loud packet.

42. A wireless transmit/receive unit (WTRU) for estimating path loss, the WTRU comprising:

a receiver for receiving a loud packet; and

a processor electrically coupled to the receiver, the processor configured to determine a signal strength of the received loud packet, a transmission power of the received loud packet, and a path loss between the first WTRU and the second WTRU, wherein the path loss is calculated by subtracting the determined signal strength from the determined transmission power.

43. The WTRU of embodiment 42, further comprising:

a transmitter electrically coupled to the processor, the transmitter configured to transmit a loud packet generation request message.

44. The WTRU of embodiment 42, further comprising:

a transmitter electrically coupled to the processor, the transmitter configured to transmit a loud packet generation response message in response to the receiver receiving a loud packet generation request message.

45. A wireless transmit/receive unit (WTRU), comprising:

a smart antenna configured to generate a plurality of antenna beams for receiving and transmitting loud packets;

a receiver electrically coupled to the smart antenna, the receiver configured to receive a loud packet generation request message;

a processor electrically coupled to the receiver, the processor configured to generate at least one loud packet based on information in the loud packet generation request message; and

a transmitter electrically coupled to the processor and the smart antenna, the transmitter configured to not transmit the at least one loud packet using an antenna beam generated by the smart antenna based on information previously obtained in the loud packet received via the smart antenna and the receiver.

46. A wireless transmit/receive unit (WTRU), comprising:

a smart antenna configured to generate a plurality of antenna beams for receiving and transmitting loud packets;

a transmitter electrically coupled to the smart antenna, the transmitter configured to transmit a loud packet generation request message;

a receiver electrically coupled to the smart antenna, the receiver configured to receive a plurality of loud packets; and

a processor electrically coupled to the transmitter and the receiver, the processor configured to determine a path loss associated with the different antenna beams used to receive the loud packet.

47. An Integrated Circuit (IC) embedded in a wireless transmit/receive unit (WTRU) for estimating path loss, the IC comprising:

a receiver configured to receive a loud packet; and

a processor electrically coupled to the receiver, the processor configured to determine a signal strength of the received loud packet, a transmission power of the received loud packet, and a path loss between the first WTRU and the second WTRU, wherein the path loss is calculated by subtracting the determined signal strength from the determined transmission power.

48. The IC of embodiment 47, further comprising:

a transmitter electrically coupled to the processor, the transmitter configured to transmit a loud packet generation request message.

49. The IC of embodiment 47 further comprising:

a transmitter electrically coupled to the processor, the transmitter configured to transmit a loud packet generation response message in response to the receiver receiving a loud packet generation request message.

50. An Integrated Circuit (IC) embedded in a wireless transmit/receive unit (WTRU) having a smart antenna configured to generate a plurality of antenna beams for receiving and transmitting loud packets, the IC comprising:

a receiver configured to receive a loud packet generation request message;

a processor electrically coupled to the receiver, the processor configured to generate at least one loud packet based on information in the loud packet generation request message; and

a transmitter electrically coupled to the processor, the transmitter configured to not transmit the at least one loud packet using an antenna beam generated by the smart antenna based on information previously obtained in the loud packet received via the smart antenna and the receiver.

51. An Integrated Circuit (IC) embedded in a wireless transmit/receive unit (WTRU) having a smart antenna configured to generate a plurality of antenna beams for receiving and transmitting loud packets, the IC comprising:

a transmitter electrically coupled to the smart antenna, the transmitter configured to transmit a loud packet generation request message;

a receiver electrically coupled to the smart antenna, the receiver configured to receive a plurality of loud packets; and

a processor electrically coupled to the transmitter and the receiver, the processor configured to determine a path loss associated with the different antenna beams used to receive the loud packet.

Although the features and elements of the present invention are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements of the present invention. While the invention has been described in terms of preferred embodiments, other variations which do not depart from the scope of the invention as claimed will become apparent to those skilled in the art.

Claims (51)

1. In a wireless communication system including a plurality of wireless transmit/receive units (WTRUs), a method of estimating path loss, the method comprising:

a first one of the WTRUs transmitting a loud packet;

receiving the loud packet by a second one of the WTRUs;

the second WTRU determining a signal strength of the received loud packet;

the second WTRU determining a transmit power of the received loud packet; and

the second WTRU determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmit power.

2. The method of claim 1 wherein the transmission power is indicated in an information field included in the loud packet.

3. The method of claim 1 wherein the wireless communication system further includes an Access Point (AP) and the transmit power is periodically broadcast by an Access Point (AP) including a field with the first WTRU's maximum transmit power.

4. The method of claim 1 wherein the wireless communication system further includes an Access Point (AP) and the second WTRU is instructed on the transmit power immediately after the second WTRU is associated with the AP.

5. The method of claim 1 wherein the loud packet includes an information field indicating the maximum transmit power of the first WTRU.

6. The method of claim 1 wherein the loud packet includes an information field including an identifier indicating the first WTRU.

7. The method of claim 6 wherein the identifier is a Media Access Control (MAC) address.

8. The method of claim 1 wherein the loud packet includes an IEEE 802.11 signaling frame.

9. The method of claim 1, further comprising:

the loud packet is piggybacked onto other types of packets.

10. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs) and a coordinating node, the method comprising:

the coordinating node transmits a loud packet generation request message;

a first one of the WTRUs receiving the loud packet generation request message;

the first WTRU transmitting at least one loud packet at a transmission power specified by the loud packet generation request message;

a second one of the WTRUs receiving the at least one loud packet;

the second WTRU determining a signal strength of the received loud packet;

the second WTRU determining a transmit power of the received loud packet; and

the second WTRU determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmit power.

11. The method of claim 10 wherein the coordinating node is an Access Point (AP).

12. The method of claim 10, further comprising the steps of:

the first WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

13. The method of claim 12 wherein the loud packet generation response message indicates the transmit power that the first WTRU will use to transmit the loud packet.

14. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs) and a coordinating node, the method comprising:

the coordinating node transmits a loud packet generation request message;

a first one of the WTRUs receiving the loud packet generation request message;

the first WTRU transmitting at least one loud packet including a message specified by the loud packet generation request message;

a second one of the WTRUs receiving the at least one loud packet;

the second WTRU determining a signal strength of the received loud packet;

the second WTRU determining a transmit power of the received loud packet based on the information contained in the loud packet; and

the second WTRU determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmit power.

15. The method of claim 14 wherein the coordinating node is an Access Point (AP).

16. The method of claim 14, further comprising the steps of:

the first WTRU generates response information in response to the loud packet generation request information by transmitting a loud packet.

17. The method of claim 16 wherein the loud packet generation response message indicates the transmit power that the first WTRU will use to transmit the loud packet.

18. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs) and a coordinating node, the method comprising:

the coordinating node transmits a loud packet generation request message;

a first one of the WTRUs receiving the loud packet generation request message;

the first WTRU transmitting at least one loud packet at a time specified by the loud packet generation request message;

a second one of the WTRUs receiving the at least one loud packet;

the second WTRU determining a signal strength of the received loud packet;

the second WTRU determining a transmit power of the received loud packet; and

the second WTRU determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmit power.

19. The method of claim 18 wherein the coordinating node is an Access Point (AP).

20. The method of claim 18, further comprising:

the first WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

21. The method of claim 20 wherein the loud packet generation response message indicates the transmit power that the first WTRU will use to transmit the loud packet.

22. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs), the method comprising:

a first one of the WTRUs transmitting a loud packet generation request message;

a second one of the WTRUs receiving the loud packet generation request message;

the second WTRU transmitting at least one loud packet at a transmission power specified by the loud packet generation request message;

a third one of the WTRUs receiving the at least one loud packet;

the third WTRU determining a signal strength of the received loud packet;

the third WTRU determining a transmit power of the received loud packet; and

the third WTRU determining a path loss between the second WTRU and the third WTRU by subtracting the determined signal strength from the determined transmit power.

23. The method of claim 22, further comprising:

the second WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

24. The method of claim 23 wherein the loud packet generation response message indicates the transmit power that the second WTRU will use to transmit the loud packet.

25. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs), the method comprising:

a first one of the WTRUs transmitting a loud packet generation request message;

a second one of the WTRUs receiving the loud packet generation request message;

the second WTRU transmitting at least one loud packet including a message specified by the loud packet generation request message;

a third one of the WTRUs receiving the at least one loud packet;

the third WTRU determining a signal strength of the received loud packet;

the third WTRU determining a transmit power of the received loud packet based on the information contained in the loud packet; and

the third WTRU determining a path loss between the second WTRU and the third WTRU by subtracting the determined signal strength from the determined transmit power.

26. The method of claim 25, comprising:

the second WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

27. The method of claim 26 wherein the loud packet generation response message indicates the transmit power that the second WTRU will use to transmit the loud packet.

28. A method of coordinating the management of loud packets used to estimate path loss in a wireless communication system including a plurality of wireless transmit/receive units (WTRUs), comprising:

a first one of the WTRUs transmitting a loud packet generation request message;

a second one of the WTRUs receiving the loud packet generation request message;

the second WTRU transmitting at least one loud packet at a time specified by the loud packet generation request message;

a third one of the WTRUs receiving the at least one loud packet;

the third WTRU determining a signal strength of the received loud packet;

the third WTRU determining a transmit power of the received loud packet; and

the third WTRU determining a path loss between the second WTRU and the third WTRU by subtracting the determined signal strength from the determined transmit power.

29. The method of claim 28, further comprising the steps of:

the second WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

30. The method of claim 29 wherein the loud packet generation response message indicates the transmit power that the second WTRU will use to transmit the loud packet.

31. In a wireless communication system including a plurality of wireless transmit/receive units (WTRUs), each WTRU including a smart antenna, a method of coordinating the management of loud packets used to estimate path loss, comprising:

a first of the WTRUs receiving a loud packet generation request message that specifies a particular antenna beam of the smart antenna for transmitting the loud packet;

the first WTRU transmitting at least one loud packet using the particular antenna beam specified by the loud packet generation request message;

a second one of the WTRUs receiving the at least one loud packet;

the second WTRU determining a signal strength of the received loud packet;

the second WTRU determining a transmit power of the received loud packet; and

the second WTRU determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmit power.

32. The method of claim 31, further comprising:

the second WTRU determines a path loss for each antenna beam of the smart antenna for receiving loud packets.

33. The method of claim 31, further comprising:

the first WTRU determines a path loss for each antenna beam of a smart antenna used to transmit the loud packet.

34. A wireless communication system that coordinates loud packet management for estimating path loss, comprising:

a coordinating node; and

a plurality of wireless transmit/receive units (WTRUs), wherein the coordinating node transmits a loud packet generation request message, a first WTRU of the WTRUs receives the loud packet generation request message and transmits at least one loud packet at a transmission power specified by the loud packet generation request message, and a second WTRU of the WTRUs receives the at least one loud packet, determines a signal strength of the received loud packet, determines a transmission power of the received loud packet, and determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmission power.

35. The system of claim 34 wherein the coordinating node is an Access Point (AP).

36. The system of claim 34 wherein the first WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

37. The system of claim 36 wherein the loud packet generation response message indicates the transmit power that the first WTRU will use to transmit the loud packet.

38. A wireless communication system that coordinates loud packet management for estimating path loss, comprising:

a coordinating node; and

a plurality of wireless transmit/receive units (WTRUs), wherein the coordinating node transmits a loud packet generation request message, a first WTRU of the WTRUs receives the loud packet generation request message and transmits at least one loud packet at a time specified by the loud packet generation request message, and a second WTRU of the WTRUs receives the at least one loud packet, determines a signal strength of the received loud packet, determines a transmission power of the received loud packet, and determines a path loss between the first WTRU and the second WTRU by subtracting the determined signal strength from the determined transmission power.

39. The system of claim 38 wherein the coordinating node is an Access Point (AP).

40. The system of claim 38 wherein the first WTRU responds to the loud packet generation request message by transmitting a loud packet generation response message.

41. The system of claim 40 wherein the loud packet generation response message indicates the transmission power that the first WTRU will use to transmit the loud packet.

42. A wireless transmit/receive unit (WTRU) for estimating path loss, the WTRU comprising:

a receiver for receiving a loud packet; and

a processor electrically coupled to the receiver, the processor configured to determine a signal strength of the received loud packet, a transmission power of the received loud packet, and a path loss between the first WTRU and the second WTRU, wherein the path loss is calculated by subtracting the determined signal strength from the determined transmission power.

43. The WTRU of claim 42 further comprising:

a transmitter electrically coupled to the processor, the transmitter configured to transmit a loud packet generation request message.

44. The WTRU of claim 42 further comprising:

a transmitter electrically coupled to the processor, the transmitter configured to transmit a loud packet generation response message in response to the receiver receiving a loud packet generation request message.

45. A wireless transmit/receive unit (WTRU), comprising:

a smart antenna configured to generate a plurality of antenna beams for receiving and transmitting loud packets;

a receiver electrically coupled to the smart antenna, the receiver configured to receive a loud packet generation request message;

a processor electrically coupled to the receiver, the processor configured to generate at least one loud packet based on information in the loud packet generation request message; and

a transmitter electrically coupled to the processor and the smart antenna, the transmitter configured to not transmit the at least one loud packet using an antenna beam generated by the smart antenna based on information previously obtained in the loud packet received via the smart antenna and the receiver.

46. A wireless transmit/receive unit (WTRU), comprising:

a smart antenna configured to generate a plurality of antenna beams for receiving and transmitting loud packets;

a transmitter electrically coupled to the smart antenna, the transmitter configured to transmit a loud packet generation request message;

a receiver electrically coupled to the smart antenna, the receiver configured to receive a plurality of loud packets; and

a processor electrically coupled to the transmitter and the receiver, the processor configured to determine a path loss associated with different antenna beams used to receive the loud packet.

47. An Integrated Circuit (IC) embedded in a wireless transmit/receive unit (WTRU) for estimating path loss, the IC comprising:

a receiver configured to receive a loud packet; and

a processor electrically coupled to the receiver, the processor configured to determine a signal strength of the received loud packet, a transmission power of the received loud packet, and a path loss between the first WTRU and the second WTRU, wherein the path loss is calculated by subtracting the determined signal strength from the determined transmission power.

48. The IC of claim 47 further comprising:

a transmitter electrically coupled to the processor, the transmitter configured to transmit a loud packet generation request message.

49. The IC of claim 47 further comprising:

a transmitter electrically coupled to the processor, the transmitter configured to transmit a loud packet generation response message in response to the receiver receiving a loud packet generation request message.

50. An Integrated Circuit (IC) embedded in a wireless transmit/receive unit (WTRU) having a smart antenna configured to generate a plurality of antenna beams for receiving and transmitting loud packets, the IC comprising:

a receiver configured to receive a loud packet generation request message;

a processor electrically coupled to the receiver, the processor configured to generate at least one loud packet based on information in the loud packet generation request message; and

a transmitter electrically coupled to the processor, the transmitter configured to not transmit the at least one loud packet using an antenna beam generated by the smart antenna based on information previously obtained in the loud packet received via the smart antenna and the receiver.

51. An Integrated Circuit (IC) embedded in a wireless transmit/receive unit (WTRU) having a smart antenna configured to generate a plurality of antenna beams for receiving and transmitting loud packets, the IC comprising:

a transmitter electrically coupled to the smart antenna, the transmitter configured to transmit a loud packet generation request message;

a receiver electrically coupled to the smart antenna, the receiver configured to receive a plurality of loud packets; and

a processor electrically coupled to the transmitter and the receiver, the processor configured to determine a path loss associated with different antenna beams used to receive the loud packet.