HK1173598B

HK1173598B - Quality of service control in multiple hop wireless communication environments

Info

Publication number: HK1173598B
Application number: HK13100315.3A
Authority: HK
Inventors: Hang Zhang; Peiying Zhu; Wen Tong; Gamini Senarath; Derek Yu; David G. Steer
Original assignee: 苹果公司
Filing date: 2008-07-14
Publication date: 2015-08-21

Description

Quality of service control in a multi-hop wireless communication environment

Priority of U.S. provisional application serial No. 60/949,767 filed on 13/7/2007 and U.S. provisional application serial No. 61/033,067 filed on 3/2008 are claimed and are incorporated herein by reference in their entirety.

Cross Reference to Related Applications

This application is related to concurrently filed U.S. application Ser. No. ______ entitled "QUALITY OF SERVICE CONTROL inside HOP COMMUNICATION Environments," which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to wireless communications, and more particularly to controlling quality of service in a multi-hop wireless communication environment.

Background

Wireless communication is already ubiquitous in modern society. Cellular networks have matured and now provide a wide range of coverage for voice communications, and are increasingly being used for data and media applications. However, the data rate of cellular networks is relatively low and therefore limited to applications that do not require high data rates, such as basic internet browsing, email, text messaging, and low resolution audio and video streaming. While such applications are useful, consumers demand richer media experiences that require significantly higher data rates, such as those provided by broadband service providers. Broadband access is typically provided by cable and telephone service providers through hard-wired cable, Digital Subscriber Line (DSL), T1, or T3 connections. Wireless access points may be coupled to a hard-wired connection to provide a local wireless zone, or hot spot, in which wireless broadband access is provided to mobile stations with complementary communication capabilities.

The Institute of Electrical and Electronics Engineers (IEEE) has set forth a widely used local wireless communication standard, which is referred to as the IEEE 802.11 standard or the wireless fidelity standard (WiFi). Unfortunately, WiFi access points have a very limited range of up to 100 to 300 feet, depending on environmental conditions. Given the limited range of WiFi, continuous coverage over a large geographic area is impractical, if not impossible. Thus, mobile users would benefit from wireless broadband access only when they are within a WiFi hotspot, which is itself limited in size.

To address WiFi limitations and provide continuous broadband access over much larger areas in a manner similar to the coverage provided by cellular networks, IEEE has set forth a next generation wireless communication standard known as the IEEE 802.16 standard or the wireless metropolitan area network standard (WiMAN). As the IEEE 802.16 standard has evolved, it has been more frequently referred to as the Worldwide Interoperability for Microwave Access (WiMAX). WiMAX promises to extend the wireless broadband access provided by a single access point to up to 30 miles for fixed stations and 3 to 10 miles for mobile stations.

In view of the extended range provided by WiMAX systems, access points are generally referred to as base stations. Although these base stations provide broadband access over a much larger area, environmental conditions may limit access in a particular area within a given coverage area. For example, geographic elements such as hills or valleys may limit access within a coverage area. Buildings or other man-made structures may also affect access throughout the coverage area. Furthermore, access within a building or public transportation vehicle (e.g., bus, train, boat, etc.) may be completely blocked, if not severely restricted.

To address these restricted access areas within the coverage area of the base station, one or more relay stations may be used to effectively extend the range of the base station. Rather than the base station communicating directly with the mobile or fixed stations of the end users, relay stations may act as contacts between these stations and the base station. One or more relay stations may be provided between the stations and a given base station, depending on the needs of the communication environment. The base station and the relay station communicate with each other using wireless communication, and the last relay station in the relay path will communicate with the mobile station or the fixed station. In addition to addressing dead spots (dead spots) in a given coverage area of a base station, relay stations may also be used to further extend the coverage area of the base station. In most cases, relay stations are less complex and less expensive than base stations; thus, it is more economical to use relay stations to extend the coverage area of a single base station than to install additional base stations and the infrastructure required to connect the base stations to the core communication network.

The relay stations may be fixed or mobile. For example, some relay stations may be permanently attached to or inside a building, while other relay stations may be installed inside different cars of a subway. To provide continuous coverage in the coverage area of a given base station, access provided to a mobile station may be transferred from one relay station to another, from a base station to a relay station, or from a base station to a relay station as the mobile station moves throughout the coverage area of the base station. Access may also be transferred from one base station to another base station or from a relay station associated with a first base station to a relay station associated with a second base station as a mobile station moves from one location to another. Similarly, a mobile relay station may be transferred from one base station to another as it moves from one location to another.

One problem that arises with the use of relay stations is the inability to effectively control the quality of service (QoS) of communications supported, at least in part, by one or more relay stations. QoS generally refers to a metric that generally affects the quality of a given communication session or access, such as delay, jitter, or data loss. When a base station communicates directly with a mobile station over an air interface, the base station and the mobile station can relatively easily cooperate with each other to both determine the communication conditions of the air interface and take steps to ensure that a given QoS level is maintained. However, adding one or more relay stations in the communication path significantly complicates QoS control because there are two or more air interfaces between the base station and the fixed or mobile stations with which the relay stations communicate. To further complicate matters, the conditions of these air interfaces may change dynamically, especially when mobile relay stations are involved.

The IEEE 802.16j standard addresses the use of relay stations and the control of communications over multiple wireless communication hops between a base station and a fixed or mobile station via one or more relay stations. However, IEEE 802.16j has not provided an effective and efficient method of providing QoS control when relay stations are involved. Thus, there is a need for a technique that provides QoS control when a relay station is used in a wireless communication environment.

Disclosure of Invention

According to one embodiment of the invention, one or more relay stations may be used along the wireless communication access path between the base station and the user terminal. The relay station that directly serves the user terminal is an access relay station and any relay station between the access relay station and the base station is an intermediate relay station. A logical communication tunnel is established between the base station and the access relay station and through any intermediate relay stations to handle session flows of Packet Data Units (PDUs) for downlink or uplink communications. A single tunnel may handle multiple session flows for the same or different user terminals. For downlink communication, the base station is the ingress station (entry station) of the tunnel and the access relay station is the egress station (egress station) of the tunnel. For uplink communications, the access relay station is the ingress station of the tunnel and the base station is the egress station of the tunnel.

Assuming that the tunnel extends through at least one intermediate relay station, the ingress station will receive the PDUs and schedule the PDUs for delivery to the first intermediate relay station of the tunnel. The PDU is then delivered via the tunnel to a first intermediate relay station in the tunnel according to a schedule (allocated). If the tunnel extends through multiple intermediate relay stations, the first intermediate relay station will receive the PDU and schedule the PDU for delivery to the next intermediate relay station of the tunnel. The PDU is then delivered to the next intermediate relay station via the tunnel according to the schedule. The last intermediate relay station in the tunnel will receive the PDU and schedule the PDU for delivery to the egress station of the tunnel. The PDU is then delivered to the egress station via the tunnel according to the schedule. If the egress station is an access relay station, the PDU is scheduled for delivery to the appropriate user terminal and then delivered via the corresponding access connection according to the schedule. If the egress station is a base station, the PDU is scheduled for delivery through the core network and then delivered according to the schedule.

As previously described, the ingress station, the egress station, and any intermediate relay stations may schedule PDUs for delivery at different hops in the wireless communication path. Such scheduling is preferably done in order to maintain appropriate QoS levels for the various session flows. However, the presence of tunnels makes it difficult for intermediate relay stations, and in some cases egress stations, to properly schedule delivery of PDUs, since these nodes cannot access any scheduling or QoS related information for the PDUs. In one embodiment of the invention, the ingress station may add scheduling information to the PDUs before they are delivered to the intermediate relay station or egress station. The scheduling information is used by the intermediate relay station to schedule the PDU for delivery to the next intermediate relay station or the egress station, as the case may be. The scheduling information may also be used by the egress station to schedule the PDUs for delivery to the corresponding user terminals. The ingress station may add scheduling information to one or more headers or sub-headers (sub-headers) of the PDUs or in the body of each PDU. The PDUs may be Medium Access Control (MAC) or other protocol level PDUs. In one embodiment, the scheduling information added to the PDU by the ingress station relates to a QoS class associated with the PDU, a deadline for the egress station to deliver the PDU to the corresponding user terminal, or a combination thereof.

In one embodiment, upon arrival of a PDU, the ingress station will determine the time of arrival of the PDU and determine the deadline for the egress station to deliver the PDU to the user terminal (for downlink) or through the core network (for uplink) based on the QoS information of the PDU. The QoS information may relate to a maximum latency (latency), or a delay to allow the PDU to reach the egress station. Based on the time of arrival and the QoS information, the ingress station will calculate a deadline for the egress station to deliver the PDU to the user terminal. Next, the ingress station will determine how long it will take for the PDU to reach the egress station through the tunnel and schedule the PDU for delivery to the first intermediate relay station in a manner that ensures that the PDU will reach the egress station before the deadline for the egress station to deliver the PDU to the user terminal (for downlink) or through the core network (for uplink).

As previously described, the ingress station may add QoS class information to the PDU, a deadline for the egress station to deliver the PDU, or both, prior to delivering the PDU to the first intermediate relay station. Upon receiving the PDU from the ingress station, the intermediate relay station may access any available QoS information or deadline information provided in the PDU. The first intermediate relay station may then determine how long it will take for the PDU to reach the egress station through the remainder of the tunnel and schedule the PDU for delivery to the next intermediate relay station or egress station (as the case may be) in a manner that ensures that the PDU will reach the egress station before the deadline for the egress station to deliver the PDU to the user terminal (for downlink) or through the core network (for uplink). Each intermediate relay station may process the PDUs in the same manner until the PDUs reach the egress station. The egress station may use the delay information in the PDU to schedule the PDU for delivery to the user terminal. The egress station will deliver the PDUs to the user terminal before the deadline for the egress station to deliver the PDUs to the user terminal (for downlink) or through the core network (for uplink). In particular, the QoS class information may be used to break a scheduling association (tie) in which multiple PDUs are scheduled for simultaneous delivery by an ingress station, an intermediate relay station, or an egress station. Preferably, the PDUs associated with the higher service class are delivered before the PDUs associated with the lower service class. Further, the scheduling or delivery deadline may be based on a particular frame or time.

Those skilled in the art will appreciate the scope of the present invention and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures.

Drawings

The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention.

Fig. 1 is a communication environment according to one embodiment of the present invention.

Fig. 2 is a block diagram representation of a wireless communication path according to one embodiment of the invention.

Figures 3A-3C provide communication flows for downlink communications according to one embodiment of the present invention.

Fig. 4 is a block diagram representation illustrating the use of a link record (log) in association with downlink communications in accordance with one embodiment of the present invention.

Fig. 5A-5C provide communication flows for uplink communications according to one embodiment of the invention.

Fig. 6 is a block diagram representation illustrating the use of link records in association with uplink communications in accordance with one embodiment of the present invention.

Fig. 7 is a block diagram representation of a base station in accordance with one embodiment of the present invention.

Fig. 8 is a block diagram representation of a user terminal according to one embodiment of the present invention.

Fig. 9 is a block diagram representation of a relay station (e.g., an access relay station or an intermediate relay station) according to one embodiment of the invention.

Detailed Description

The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the invention and illustrate the best mode of practicing the invention. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the invention and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

Referring to fig. 1, a wireless communication environment 10 is illustrated in accordance with one embodiment of the present invention. As depicted, various User Terminals (UTs) 12 may communicate through a core network 14 via corresponding Base Station Controllers (BSCs) 16, Base Stations (BSs) 18, and one or more relay stations. Depending on the location and function of the relay station, the relay station may be considered as an intermediate relay station (IR)20 or an access relay station (AR) 22. User terminal 12 may represent a mobile or fixed terminal capable of supporting wireless communications with one or more of base station 18 and access relay 22. Intermediate relay stations 20 and access relay stations 22 also support wireless communications. In particular, the access relay station 22 will support wireless communications with the user terminal 12 and with the intermediate relay station 20 or base station 18. One or more intermediate relay stations 20 will exist between the base station 18 and the access relay station 22, and will facilitate wireless communication with the base station 18, with the access relay station 22, or both.

Thus, the user terminal 12 may communicate directly with the base station 18 or the access relay 22. As illustrated, user terminal 12A is served directly by base station 18. The user terminals 12B, 12C and 12D are served by different access relay stations 22. The access relay 22 serving the user terminal 12B is served directly by the base station 18. The user terminal 12C is served by an access relay station 22 linked to the base station 18 by a single intermediate relay station 20. The user terminal 12D is served by an access relay station 22 coupled to the base station 18 through two intermediate relay stations 20. Thus, user terminals 12 may be served by either base station 18 or access relay station 22, and any number of intermediate relay stations 20 may be provided to wirelessly connect base station 18 with a given access relay station 22.

Preferably, the user terminal 12 is capable of moving around within the communication environment 10 and is therefore served by different access relay stations 22 and base stations 18 depending on its location. Further, the access relay 22 may be mobile or fixed. Thus, the access relay 22 may transition from being served directly by one base station 18 to being served by another base station 18 or an intermediate relay 20. The mobile access relay station 22 may also be transferred from one intermediate relay station 20 to another.

Communication between the base station 18, the intermediate relay station 20, the access relay station 22 and the user terminal 12 is provided via a wireless communication link. Each communication link is considered a "hop. When a user terminal 12, such as user terminal 12A, is served directly by base station 18, the access path is considered to be a single-hop wireless communication path. When one or more relay stations are present in an access path, the access path is considered to be a multi-hop wireless communication path. Thus, the access path between the user terminal 12B and its serving base station 18 is a two-hop wireless communication path. The access path between user terminal 12C and its serving base station 18 is considered a three-hop wireless communication path, while the access path between user terminal 12D and its serving base station 18 is considered a four-hop wireless communication path.

For a single-hop wireless communication path, the user terminal 12 and the base station 18 are able to communicate with each other and determine channel conditions or other factors that may affect the exchange of data between the two entities. When only a single wireless communication link is addressed, the base station 18 can relatively easily determine the channel conditions associated with the wireless communication link and schedule downlink communications to the user terminals 12 as well as uplink communications from the user terminals 12 to ensure that an appropriate quality of service (QoS) level is maintained. However, when a relay station is used, multiple hops, and therefore multiple wireless communication links, exist between the base station 18 and the corresponding user terminals 12. Although the base station 18 may be able to obtain an indication of the channel conditions between the base station 18 and the relay station in direct communication with the base station 18, the channel conditions for the wireless communication link between the relay station and the user terminal 12 or other relay stations cannot be directly accessed by the base station 18. These channel conditions may change dynamically and constantly, taking into account the mobility capabilities of certain relay stations and user terminals 12. Thus, scheduling uplink and downlink transmissions in a manner that ensures that a particular QoS level is maintained has proven challenging.

In many cases, different user terminals 12 may require different QoS levels. Further, different types of communications may be associated with different QoS levels. For example, different subscribers may pay at different rates for different overall QoS levels. In addition, certain media applications (e.g., streaming audio and video, as well as voice) may require a higher QoS level than certain web browsing or file transfer applications. In most cases, the portion of the communication path that is likely to change is the portion of the radio access that exists between the base station 18 and the user terminal 12, either directly or through one or more relay stations. The present invention therefore employs techniques to take into account the effects of various wireless communication links along a wireless access path to control the scheduling of uplink and downlink communications according to QoS requirements.

Referring to fig. 2, one or more relay stations may be used along the wireless communication access path between base station 18 and user terminal 12. Wireless relay links 24 are provided between the base stations 18 and the intermediate relay stations 20 and between the intermediate relay stations 20 and the access relay stations 22. A wireless access link 26 is provided between the access relay station 22 and the user terminal 12. If multiple intermediate relay stations 20 are provided in the wireless communication access path, relay links 24 are also established between the intermediate relay stations 20. As previously described, the relay station that directly serves the user terminal 12 is the access relay station 22, and any relay station between the access relay station 22 and the base station 18 is the intermediate relay station 20. A logical communication tunnel is established between the base station 18 and the access relay 22 and through one or more intermediate relays 20 to handle a session flow of PDUs for downlink or uplink communications. This tunnel is referred to as the BS-AR tunnel 28, and different tunnels may be used for uplink and downlink communications. The BS-AR tunnel 28 may handle multiple session flows for the same or different user terminals 12. For downlink communications, the base station 18 is the ingress station of the BS-AR tunnel 28 and the access relay station 22 is the egress station of the BS-AR tunnel 28. For uplink communications, the access relay station 22 is the ingress station of the BS-AR tunnel 28 and the base station 18 is the egress station of the BS-AR tunnel 28.

Assuming that the BS-AR tunnel 28 extends through at least one intermediate relay station 20 as described, the ingress station will receive the PDUs and schedule the PDUs for delivery to the first intermediate relay station 20 of the tunnel. The PDU is then delivered to the first intermediate relay station 20 in the BS-AR tunnel 28 via the BS-AR tunnel 28 according to the schedule. If the BS-AR tunnel 28 extends through multiple intermediate relay stations 20 (not shown in fig. 2), the first intermediate relay station 20 will receive the PDUs and schedule the PDUs for delivery to the next intermediate relay station 20 of the BS-AR tunnel 28. The PDU is then delivered to the next intermediate relay station 20 via the tunnel according to the schedule. The last intermediate relay station 20 in the BS-AR tunnel 28 will receive the PDU and schedule the PDU for delivery to the egress station. The PDUs are then delivered to the egress station via the BS-AR tunnel 28 according to the schedule. If the egress station is an access relay station 22, the PDU is scheduled for delivery to the appropriate user terminal 12 and then the PDU is delivered via the corresponding access connection 30 according to the schedule, where the access connection 30 is provided over the access link 26. If the egress station is a base station 18, the PDU is scheduled for delivery through the core network 14 and then delivered according to the schedule.

As previously described, the ingress station, the egress station, and any intermediate relay stations 20 may schedule PDUs for delivery at different hops in the wireless communication path. Such scheduling is preferably done in order to maintain appropriate QoS levels for the various session flows. However, the presence of the BS-AR tunnel 28 makes it difficult for the intermediate relay station 20, and in some cases the egress station, to properly schedule delivery of the PDUs, since these nodes typically do not have access to any scheduling or QoS related information for the PDUs. In one embodiment of the invention, the ingress station may add scheduling information to the PDUs before they are delivered to the intermediate relay station 20 or the egress station. The scheduling information is used by the intermediate relay station 20 to schedule the PDUs for delivery to the next intermediate relay station 20 or the egress station, as the case may be. The scheduling information may also be used by the egress station to schedule the PDUs for delivery to the corresponding user terminals 12. The ingress station may add scheduling information to the header or body of each PDU. In one embodiment, the scheduling information added to the PDU by the ingress station relates to the QoS class associated with the PDU, the deadline for the egress station to deliver the PDU to the corresponding user terminal 12 (for downlink) or through the core network 14 (for uplink), or a combination thereof.

Upon arrival of the PDU, the ingress station will determine the time of arrival of the PDU and, based on the QoS information of the PDU, determine the deadline for the egress station to deliver the PDU to the user terminal 12 (for downlink) or through the core network 14 (for uplink). The QoS information may relate to a maximum latency, or a delay to allow the PDUs to reach the egress station. Based on the time of arrival and the QoS information, the ingress station will calculate a deadline for the egress station to deliver the PDU to the user terminal 12 (for the downlink) or through the core network 14 (for the uplink). Next, the ingress station will determine how long it will take for the PDU to reach the egress station through the tunnel and schedule the PDU for delivery to the first intermediate relay station 20 in a manner that ensures that the PDU will reach the egress station before the deadline for the egress station to deliver the PDU to the user terminal 12 (for downlink) or through the core network 14 (for uplink).

As previously described, the ingress station may add QoS class information to the PDUs prior to delivery to the first (and only shown) intermediate relay station 20, a deadline for the egress station to deliver the PDUs to the user terminal 12 (for the downlink) or through the core network 14 (for the uplink), or both. Upon receiving the PDU from the ingress station, the first intermediate relay station 20 may access any available QoS information or deadline information provided in the PDU. The first intermediate relay station 20 may then determine how long it will take for the PDU to reach the egress station through the remainder of the tunnel and schedule the PDU for delivery to the next intermediate relay station 20 (not shown) or egress station (as shown) (as the case may be) in a manner that ensures that the PDU will reach the egress station before the deadline for the egress station to deliver the PDU to the user terminal 12 (for the downlink) or through the core network 14 (for the uplink). Each intermediate relay station 20 may process the PDUs in the same manner until the PDUs reach the egress station. The egress station may use the delay information in the PDU to schedule the PDU for delivery to the user terminal 12 (for the downlink) or through the core network 14 (for the uplink). The egress station will deliver the PDUs by the deadline for the egress station to deliver the PDUs to the user terminal 12 (for the downlink) or through the core network 14 (for the uplink). In particular, the QoS class information may be used to break a scheduling relationship in which multiple PDUs are scheduled for simultaneous delivery by the ingress station, the intermediate relay station 20, or the egress station. Preferably, the PDUs associated with the higher service class are delivered before the PDUs associated with the lower service class. Further, the scheduling or delivery deadline may be based on a particular frame or time.

With reference to fig. 3A-3C, communication flows in accordance with one embodiment of the present invention are provided to illustrate an exemplary scheduling process for downlink communications. In this example, the wireless communication access path is assumed to be the same as or similar to that shown in fig. 2. The communication flow illustrates the processing of a given PDU received from the core network 14 through the base station controller 16. Initially, an incoming PDU is received and then processed by the base station 18 (steps 100 and 102). The base station 18 will note the time of arrival of the PDU at the base station 18, andstoring information related to the time of arrival as a base station time of arrival (t)_BSA) (step 104).

As indicated above, a PDU is one of a plurality of PDUs that make up a session flow for a given communication session. A service flow may be assigned to one of any number of defined QoS classes. Each class will be associated with various QoS parameters that should control how PDUs for a given session flow are processed for uplink or downlink communications. The QoS parameters are stored in a QoS profile for a particular QoS class. In one embodiment, the QoS parameters provided in the QoS class define latency information, which refers to the base station arrival time t_BSAAnd access link delivery deadline (t)_ADL) And corresponds to the time between: at or before which time the PDUs should be transmitted directly to the user terminal 12 over the access link.

In particular, when a session flow is established, the serving node in the core network 14 will assign a QoS class to the service flow. The serving node may provide the base station 18 with class identification information for the service flow, where the base station 18 will be able to analyze the information provided in the PDU and identify the QoS class of the service flow to which the PDU belongs. While a service flow is being established, the base station 18 may access the corresponding QoS profile to obtain corresponding QoS class identification information. In this way, the base station 18 may gather information from the PDUs to determine the service flow to which the PDUs belong, and then determine the QoS class of the service flow. Alternatively, the PDUs may include information relating to the appropriate QoS class, and the base station 18 may identify the appropriate QoS class based on information provided in the PDUs themselves.

Regardless of the technology, the base station 18 will identify the QoS class information for the PDU (step 106) and access a QoS profile for the PDU based on the class information (step 108). From the QoS profile, the base station 18 may obtain latency information (t) from the QoS profile_LAT) (step 110). Based on base station time of arrival (t)_BSA) And latency information (t)_LAT) The base station 18 may determine an access link delivery deadline (t)_ADL) (step 112). Access link delivery deadline t_ADLCorresponds to energyThe latest time or frame that the PDU can be delivered from the access relay station 22 to the user terminal 12. If the waiting time information t_LATAccess link delivery deadline t corresponding to a maximum allowed time since the PDU arrived at base station 18 and a time since the PDU should be transmitted from access relay station 22_ADLCan be controlled by setting the waiting time information t_LATAdded to the base station arrival time t_BSAIs calculated where t_ADL＝t_BSA+t_LAT。

At this point, the base station 18 knows the latest time or frame at which the PDU should be transmitted from the access relay station 22. However, there are two relay links 24 between the base station 18 and the access relay 22. Thus, in order for the base station 18 to ensure that the PDUs arrive at the access relay 22 in time to deliver the deadline t at the access link_ADLBefore being transmitted to the user terminal 12, the base station 18 needs to ensure that the PDUs are transmitted to the intermediate relay station 20 in sufficient time to allow the intermediate relay station 20 to deliver the deadline t on the access link_ADLThe PDUs are previously delivered to the access relay 22. Thus, the base station 18 will deliver the deadline T based on the access link_ADLAnd BS-AR propagation information (t)_BS-AR) To calculate a first relay link delivery deadline (t)_RDL1) (step 114). First relay link delivery deadline t_RDL1Corresponding to the last time or frame that the PDU can be transmitted by the base station 18 to the intermediate relay station 20 and still maintain the desired QoS level. BS-AR propagation information t_BS-ARCorresponding to the time it takes for a PDU transmitted from the base station 18 to propagate through the relay link 24 and the intermediate relay station 20 to the access relay station 22. Therefore, the BS-AR propagates the information t_BS-ARThe BS-AR tunnel 28 extends between the base station 18 and the access relay 22 corresponding to the time it takes for the PDU to traverse the BS-AR tunnel 28. In this example, the first relay link delivery deadline t_RDL1The deadline t may be delivered by a delivery from the access link_ADLSubtracting BS-AR propagation information t_BS-ARTo determine where t is_RDL1＝t_ADL-t_BS-AR。

At this point, the base station 18 knows that the PDU can be delivered to the intermediate relay station 20 and still meet QoS the last time or frame required. Because the base station 18 will process multiple PDUs for multiple session flows, the base station 18 will provide these steps for each PDU and determine when to transmit the respective PDU to the respective intermediate relay station 20, access relay station 22, or user terminal 12, depending on the number of hops in the wireless communication path. In one embodiment, the delivery deadline t is based on a first relay link_RDL1To schedule each PDU to be transmitted at a particular time or in a particular frame.

Before transmitting the PDU to the intermediate relay station 20, the base station 18 will transmit the QoS class information and the access link delivery deadline t in one or more headers or sub-headers or actual bodies of the information carried in the PDU_ADLAttached to the PDU (step 116). In a preferred embodiment, the QoS class information and the access link delivery deadline are provided in the same or different subheaders in a Medium Access Control (MAC) PDU. By providing QoS class information and access link delivery deadline t in a PDU_ADLThe intermediate relay station 20 can identify the QoS class associated with the PDU and deliver the deadline t using the access link_ADLTo determine when the PDUs should be transmitted to the access relay 22 in order to maintain the desired QoS level. Thus, the base station 18 will deliver the deadline t on the first link_RDL1Or previously transmit the PDU to the intermediate relay station 20 (step 118). In particular, if multiple PDUs for different session flows have the same first link delivery deadline t_RDL1The base station 18 may use the QoS class information to decouple the PDU delivery time. Those PDUs associated with a higher QoS class will be transmitted to the appropriate intermediate relay station 20 (or other appropriate relay station or user terminal) before the PDUs associated with a lower QoS class.

Next, the intermediate relay station 20 will receive a PDU that includes QoS class information and an access link delivery deadline t_ADL(step 120). The intermediate relay station 20 will then deliver the deadline t based on the access link_ADLAnd IR-AR propagation information (t)_IR-AR) To calculate a second relay link delivery deadline (t)_RDL2) (step 122). Second relay link delivery bestAfter time limit t_RDL2Corresponding to the latest time or frame that the PDU should be transmitted to the access relay 22 in order to maintain the required QoS level. For example, the second relay link delivery deadline t_RDL2The deadline t may be delivered by a delivery from the access link_ADLSubtracting the IR-AR propagation information t_IR-ARTo calculate, wherein: t is t_RDL2＝t_ADL-t_IR-AR。

The intermediate relay station will then deliver the deadline t on the second relay link_RDL2Or previously transmit the PDU to the access relay 22 (step 124). Also, the QoS class information for individual PDUs may be used to de-associate PDUs with the same relay link delivery deadline. In particular, the PDU will be associated with QoS class information and access link delivery deadline t_ADLAre delivered to the access relay 22 together (step 126). The access relay 22 will deliver the deadline t on the access link_ADLOr previously transmit the PDU to the user terminal 12 (step 128). Access relay 22 may disassociate PDUs with the same access link delivery deadline based on the QoS class associated with the respective PDU. The PDUs may be delivered to the user terminal 12 over the access link 26 and the appropriate access connection 30 with or without QoS class information or access link delivery deadline (step 130).

As described above, the BS-AR propagates the information t_BS-ARTo the amount of time it takes for the PDU to travel from the base station 18 to the access relay 22; however, it is not necessarily measured in units of time. For delivery of scheduled PDUs to the intermediate relay station 20, the base station 18 propagates the information t using the BS-AR_BS-ARA first relay link delivery deadline is calculated. BS-AR propagation information t_BS-ARCan be determined in various ways by using different types of information. For example, each hop between the base station 18 and the access relay 22 may be associated with a standardized delivery time t_normAssociated and taking into account the standardized delivery time t for each hop_normIn the case of (3), B S-AR propagates the information t_BS-ARMay be based solely on the number of hops n between the base station 18 and the access relay 22. Therefore, the BS-AR propagates the information t_BS-ARCan be determined as follows:

equation 1t_BS-AR＝n*t_norm.

BS-AR propagates information t if an actual or average delivery time is available for each hop_BS-ARMay be based on these delivery times. Using the example above, the BS-AR propagates the information t_BS-ARCan be determined as follows:

equation 2t_BS-AR＝t_hop1+t_hop2，

Wherein t is_hop1Represents the actual or average delivery time that the PDU was delivered from the base station 18 to the intermediate relay station 20, and t_hop2Representing the actual or average delivery time of the PDUs delivered from the intermediate relay station 20 to the access relay station 22.

Similarly, IR-AR propagates information t_IR-ARTo the amount of time it would take for a PDU to travel from the intermediate relay station 20 to the access relay station 22. For the delivery of the scheduling PDU to the access relay 22, the intermediate relay 20 propagates the information t using IR-AR_IR-ARTo calculate a second relay link delivery deadline t_RDL2. IR-AR propagation information t_IR-ARInformation t can be propagated with BS-AR_BS-ARIn a similar manner. For example, each hop remaining between intermediate relay station 20 and access relay station 22 may be associated with a normalized delivery time t_normAssociated and taking into account the normalized delivery time t for the remaining hops_normIn case of (2), the BS-AR propagates the information t_BS-ARMay be based only on the number of hops m remaining between the base station 18 and the access relay 22. Therefore, the BS-AR propagates the information t_BS-ARCan be determined as follows:

equation 3t_BS-AR＝m*t_norm.

IR-AR propagates information t if actual or average delivery time is available for the remaining hop(s)_IR-ARMay be based on these delivery times. Using the example above, the IR-AR propagates the information t_IR-ARCan be determined as follows:

equation 4T_IR-AR＝t_hop2，

Wherein t is_hop2Also representing the actual or average delivery time of the PDU from the intermediate relay station 20 to the access relay station 22.

The BS-AR and IR-AR propagation information may be obtained by the base station 18 or the intermediate relay station 20 in various ways. For the standardized information, each station may get the number of hops to the access relay station 22 and use the standardized time of hop (hop time) for the corresponding calculation. In more complex embodiments, link performance based on actual or average time hops may be exchanged between stations. For example, access relay station 22 may monitor access link metrics of access link 26 and report the access link metrics to intermediate relay station 20. The intermediate relay station 20 may monitor relay link metrics for the relay links 24, which relay links 24 exist between the intermediate relay station 20 and the access relay station 22. Based on the relay link metrics, the intermediate relay station 20 can determine the hop time of the relay link 24, which relay link 24 exists between the access relay station 22 and the intermediate relay station 20. Thus, the relay link metric for the relay link 24 between the intermediate relay station 20 and the access relay station 22 may represent or be used to determine the BS-AR propagation information t_IR-AR。

Intermediate relay station 20 may also provide base station 18 with relay link metrics for relay link 24 between intermediate relay station 20 and access relay station 22, as well as access link metrics. The base station 18 may monitor relay link metrics of relay links 24 existing between the intermediate relay stations 20 and the base station 18 and determine the time hops of the relay links 24 existing between the base station 18 and the intermediate relay stations 20. As previously described, the base station 18 receives relay link metrics from the intermediate relay station 20 for the relay link 24 between the intermediate relay station 20 and the access relay station 22. Thus, the base station 18 has relay link metrics for the two relay links 24 that exist between the base station 18 and the access relay 22. The relay link metrics for these relay links 24 may represent or be used to determine the BS-AR propagation information t_BS-AR。

The BS-AR and IR-AR propagation information may take various forms and be derived from different types of relay link metrics. For example, the relay link metric for a given relay link may represent a set of transmission times, delays, or throughputs on the link for PDUs belonging to a given QoS class (regardless of the destination of the PDUs), PDUs transmitted to or from a given user terminal 12, PDUs associated with a given service flow, PDUs associated with a given type of service flow, and so forth. The relay link metrics for the multiple relay links 24 may be further aggregated to determine a standardized link metric for some or all of the relay links 24 along the BS-AR tunnel 28.

Referring to fig. 4, a link record LL for a downlink session flow may be used to deliver link metrics from one station to another. The relay link metric may represent, correspond to, or be used to derive, BS-AR propagation information or IR-AR propagation information, which is used for scheduling as described in connection with the examples provided in fig. 3A-3C. The link record LL may be configured as a template with fields that can be filled by different stations for different link metrics. For downlink session flows, access link metrics (AR-UTs) may be provided by access relay station 22 in a first field of link record LL. The access relay station 22 will forward the link record LL to the intermediate relay station 20. The relay link metric (IR-AR) for the relay link 24 between the intermediate relay station 20 and the access relay station 22 may be provided by the intermediate relay station 20 in a second field in the link record LL. The intermediate relay station 20 will forward the populated link record LL to the base station 18, where the link record LL may have access link metrics (AR-UT) for the relay link 24 existing between the intermediate relay station 20 and the access relay station 22, as well as relay link metrics (IR-AR). As previously indicated, the base station 18 may monitor the relay link metric (BS-IR) of the relay link 24 existing between the intermediate relay station 20 and the base station 18. Thus, the base station 18 will derive relay link metrics for each relay link 24 between the base station 18 and the access relay station 22. The link record LL will support any number of intermediate relay stations 20.

For the communication flow described in connection with fig. 3A-3C, the base station 18 is the ingress station and the access relay station 22 is the egress station, and thus PDUs flow from the base station 18 to the access relay station 22 through the BS-AR tunnel 28. The present invention is equally applicable to uplink communications where the access relay station 22 is an ingress station and the base station 18 is an egress station. Thus, the PDUs are delivered from the access relay 22 to the base station 18 via an AR-BS tunnel through one or more intermediate relays 20. The AR-BS tunnel is not shown, but is similar to the BS-AR tunnel 28. The reverse of the nomenclature BS-AR to AR-BS indicates the direction of the service flow. An example of how the present invention applies to uplink communications is provided in the communication flows of fig. 5A-5C.

For a given service flow, access relay station 22 may obtain corresponding QoS class information or QoS profiles from base station 18 through intermediate relay station 20 (steps 200 and 202). This information may be provided directly by the base station 18 or obtained by the access relay 22 from another serving node based on information received from the base station 18. Access relay 22 may identify latency information t from the QoS profile_LAT(step 204). As described above, the waiting time information t_LATCorresponding to the maximum amount of time allowed for the PDUs to travel from the access relay 22 to the base station 18 through the AR-BS tunnel. When the access relay 22 receives a PDU for a corresponding service flow from the user terminal 12 (step 206), the access relay 22 will identify and store the access relay arrival time (t)_ARA) (step 208). The access relay 22 will then be based on the access relay arrival time t_ARAAnd waiting time information t_LATTo determine a network delivery deadline (t)_NDL) (step 210). Network delivery deadline t_NDLRepresents the time or frame before or at which the PDUs must be delivered by the base station 18 through the core network 14. For example, the network delivery deadline t_NDLCan be determined by comparing the waiting time information t_LATAdded to the access relay arrival time t_ARAIs calculated where t_NDL＝t_ARA+t_LAT。

In this regard, the access relay 22 knows when it must be delivered by the base station 18 through the core network 14A PDU. The access relay 22 must then take steps to ensure that the PDU is delivered at the network delivery deadline t_NDLAnd previously delivered to the base station 18. In one embodiment, the access relay 22 will deliver the time t based on the network_NDLAnd AR-BS propagation information (t)_AR-BS) To calculate a second relay link delivery deadline (t)_RDL2) (step 212). Second relay link delivery deadline t_RDL2Indicating a time or frame before or at which the PDU should be delivered to the intermediate relay station 20 over the second relay link 24. AR-BS propagation information t_AR-BSCorresponding to the amount of time it takes for the PDU to travel from the access relay 22 to the base station 18 via the AR-BS tunnel. In this example, the second relay link delivery deadline t_RDL2By delivering the deadline t from the network_NDLSubtracting the AR-BS propagation information t_AR-BSIs calculated where t_RDL2＝t_NDL-t_AR-BS。

At this point, the access relay 22 knows the last time or frame that the PDU should be delivered to the intermediate relay 20. Before delivering the PDU to the intermediate relay station 20, the access relay station 22 will append QoS class information and network delivery deadline t in the header or body of the PDU_NDL(step 214). The access relay 22 will then deliver the deadline t on the second relay link_RDL2Or previously transmits the PDU to the intermediate relay station 20 (step 216). In a preferred embodiment, the QoS class information and the network link delivery deadline are provided in the same or different subheaders in the mac pdu; however, this information may be delivered with the PDU in any manner. If multiple PDUs from the same or different user terminals 12 end up with the same second Relay Link delivery deadline t_RDL2The QoS class information associated with the PDU may be used to decouple the PDU delivery time. Thus, the PDUs are delivered to the intermediate relay station 20 and will include QoS class information and network delivery deadline t_NDL(step 218).

At this point, the intermediate relay station 20 must schedule the PDUs for delivery to the base station 18 so that the PDUs are delivered to the base station sufficiently in timeStation 18 for base station 18 to deliver deadline t on network_NDLThe PDUs are previously delivered through the core network 14. Thus, the intermediate relay station 20 will deliver the deadline t based on the network_NDLAnd IR-BS propagation information (t)_IR-BS) To calculate a first relay link delivery deadline (t)_RDL1) (step 220). The intermediate relay station 20 may recover the network delivery deadline t from the PDU_NDL. IR-BS propagation information t_IR-BSTo the amount of time it takes for the PDU to travel from the intermediate relay station 20 to the base station 18 through the remainder of the AR-BS tunnel. In this example, assume that the first relay link delivery deadline t_RDL1Is by delivering the deadline t from the network_NDLSubtracting the IR-BS propagation information t_IR-BSIs calculated where t_RDL1＝t_NDL-t_IR-BS。

At this point, the intermediate relay station 20 knows to schedule the PDUs for delivery of the deadline t on the first relay link_RDL1Or previously delivered to the base station 18. Likewise, a delivery deadline may correspond to a time or frame at or before which a PDU must be delivered. Thus, the intermediate relay station 20 will deliver the deadline t at the first relay link_RDL1Or previously transmit the PDU to the base station 18 (step 222). Also, the QoS class information provided by the access relay 22 in the PDU may be used to decouple the PDU delivery time. The PDU is delivered to the base station 18 and will include QoS class information and a network delivery deadline t_NDL(step 224). The base station 18 will provide the network delivery deadline t in the PDU_NDLOr previously transmit the PDU through the core network 14 (step 226). Also, QoS class information provided in or otherwise known to the base station 18 may be used to decouple PDU delivery times. Thus, the base station 18 will deliver the PDU through the core network 14 (step 228).

Referring to fig. 6, a link record LL for an uplink session flow may be used to deliver link metrics from one station to another. The relay link metric may represent, correspond to, or be used to derive AR-BS propagation information or IR-BS propagation information, which is used for scheduling as described in connection with the examples provided in fig. 5A-5C. As for the link record LL for the downlink session flow, the uplink link record LL may be configured as a template with fields that can be populated by different stations for different link metrics. For uplink session flows according to the illustrated example, the relay link metric (IR-BS) for the relay link 24 between the intermediate relay station 20 and the base station 18 may be provided by the intermediate relay station 18 in the first field of the link record LL. Intermediate relay station 20 may forward the populated link record LL to access relay station 22, where link record LL will have a relay link metric (IR-BS) for relay link 24 that exists between intermediate relay station 20 and base station 18. The access relay station 22 may monitor a relay link metric (IR-AR) of a relay link 24 existing between the intermediate relay station 20 and the access relay station 22. Thus, the access relay station 22 will derive a relay link metric for each relay link 24 between the access relay station 22 and the base station 18. The link record LL will support any number of intermediate relay stations 20.

A high-level overview of the base station 18, the user terminal 12 and the relay station (e.g., intermediate relay station 20 or access relay station 22) is provided below in connection with fig. 7, 8 and 9. And more particularly to fig. 7, a base station 18 configured in accordance with one embodiment of the present invention is illustrated. The base station 18 generally includes a control system 32, a baseband processor 34, transmit circuitry 36, receive circuitry 38, one or more antennas 40, and a network interface 42. Receive circuitry 38 receives radio frequency signals bearing information from one or more remote transmitters provided by user terminals 12, intermediate relay stations 20, or access relay stations 22. Preferably, a low noise amplifier and filter (not shown) cooperate to amplify the signal and remove broadband interference from the signal for processing. Downconversion and digitization circuitry (not shown) will then downconvert the filtered, received signal to an intermediate or baseband frequency signal, which is then digitized into one or more digital streams.

The baseband processor 34 processes the digitized received signal to extract the information or data bits carried in the received signal. This processing typically includes demodulation, decoding, and error correction operations. Thus, the baseband processor 34 is typically implemented in one or more Digital Signal Processors (DSPs). The received information is then sent to the core network 14 via the network interface 42 or communicated to another user terminal 12 served by the base station 18. The network interface 42 will typically interact with the core network 14 via the base station controller 16.

On the transmit side, the baseband processor 34, under control of the control system 32, receives digitized data, which may represent voice, data, or control information, from the network interface 42, which encodes the data for transmission. The encoded data is output to transmit circuitry 36 where a modulator uses the data to modulate a carrier signal at the desired transmit frequency(s). A power amplifier (not shown) will amplify the modulated carrier signal to a level suitable for transmission and deliver the modulated carrier signal to one or more antennas 40 through a matching network.

Reference is made to fig. 8, which illustrates a fixed or mobile user terminal 12 configured in accordance with an embodiment of the present invention. The user terminal 12 will include a control system 44, a baseband processor 46, transmit circuitry 48, receive circuitry 50, one or more antennas 52, and user interface circuitry 54. Receive circuitry 50 receives radio frequency signals bearing information from one or more remote transmitters provided by either base station 18 or access relay station 22. Preferably, a low noise amplifier and filter (not shown) cooperate to amplify the signal and remove broadband interference from the signal for processing. Downconversion and digitization circuitry (not shown) will then downconvert the filtered, received signal to an intermediate or baseband frequency signal, which is then digitized into one or more digital streams. The baseband processor 46 processes the digitized received signal to extract the information or data bits carried in the received signal. This processing typically includes demodulation, decoding, and error correction operations. The baseband processor 46 is typically implemented in one or more Digital Signal Processors (DSPs).

For transmission, the baseband processor 46 receives digitized data, which may represent voice, data, or control information, from the control system 44, which encodes the data for transmission. The encoded data is output to transmit circuitry 48, where a modulator uses the data to modulate a carrier signal at the desired transmit frequency(s). A power amplifier (not shown) will amplify the modulated carrier signal to a level suitable for transmission and deliver the modulated carrier signal to one or more antennas 52 through a matching network. Various modulation and processing techniques available to those skilled in the art are suitable for the present invention.

Referring to fig. 9, a relay station 56 configured in accordance with one embodiment of the present invention is illustrated. The relay station may represent an intermediate relay station 20 or an access relay station 22. The relay station 56 generally includes a control system 58, a baseband processor 60, transmit circuitry 62, receive circuitry 64, and one or more antennas 66. Receive circuitry 64 receives radio frequency signals bearing information from one or more remote transmitters provided by user terminals 12, other intermediate relay stations 20, or access relay stations 22 or base stations 18. Preferably, a low noise amplifier and filter (not shown) cooperate to amplify the signal and remove broadband interference from the signal for processing. Downconversion and digitization circuitry (not shown) will then downconvert the filtered, received signal to an intermediate or baseband frequency signal, which is then digitized into one or more digital streams.

The baseband processor 60 processes the digitized received signal to extract the information or data bits carried in the received signal. This processing typically includes demodulation, decoding, and error correction operations. Thus, the baseband processor 60 is typically implemented in one or more Digital Signal Processors (DSPs). The received information is then transmitted to the user terminal 12, intermediate relay station 20, access relay station 22, or base station 18 as described below.

On the transmit side, the baseband processor 60 receives digitized data, which may represent voice, data, or control information, for transmission. The digitized data is encoded and the encoded data is output to transmit circuitry 62, where the modulator uses the data to modulate a carrier signal at the desired transmit frequency(s). A power amplifier (not shown) will amplify the modulated carrier signal to a level suitable for transmission and deliver the modulated carrier signal to one or more antennas 66 through a matching network.

Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present invention. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

Claims

1. An ingress station residing in a wireless communication access path in a wireless communication environment, wherein a tunnel is established with an egress station through one or more intermediate relay stations along the wireless communication access path, the ingress station comprising:

a wireless communication circuit;

a control system associated with the wireless communication circuitry and adapted to:

receiving a plurality of packet data units associated with at least one service flow supported by the tunnel;

for each packet data unit of the plurality of packet data units:

determining an egress station delivery deadline by which or before the egress station delivery deadline an egress station should deliver the packet data unit to a destination of the packet data unit;

providing an egress station delivery deadline with the packet data unit; and

the packet data unit is delivered via the tunnel with the egress station delivery deadline to an intermediate relay station of the one or more relay stations.

2. The ingress station of claim 1 wherein the control system is further adapted to determine an ingress station delivery deadline for the packet data unit at or before which the ingress station should deliver the packet data unit to the intermediate relay station to ensure that the packet data unit reaches the egress station in sufficient time to be delivered to the destination of the packet data unit by the egress station delivery deadline.

3. The ingress station of claim 2 wherein to determine the ingress station delivery deadline for the packet data unit, the control system is further adapted to:

determining propagation information relating to how long it may take a packet data unit to be delivered to an egress station through one or more intermediate relay stations; and

an ingress station delivery deadline is calculated based on the propagation information and the egress station delivery deadline.

4. The ingress station of claim 3 wherein the ingress station delivery time is calculated at least in part by subtracting the propagation information from the egress station delivery deadline.

5. The ingress station of claim 3 wherein the control system is further adapted to receive a propagation metric related to at least one link between the ingress station and the egress station, and wherein the control system determines the propagation information based on the propagation metric.

6. The ingress station of claim 5 wherein the propagation metric relates to a link between the intermediate relay station and the egress station.

7. The ingress station of claim 5 wherein the propagation metric for at least one link is provided by the intermediate relay station in a record having a different field for the propagation metric for each link reported.

8. The ingress station of claim 2 wherein the control system is further adapted to deliver the packet data unit to the intermediate relay station via the tunnel with the egress station delivery deadline at or before the ingress station delivery deadline.

9. The ingress station of claim 2 wherein when a number of packet data units of the plurality of packet data units have the same ingress station delivery deadline, quality of service class information associated with the number of packet data units is used to control an order in which the number of packet data units are delivered to the intermediate relay station.

10. The ingress station of claim 1 wherein to determine the egress station delivery deadline for the packet data unit, the control system is further adapted to:

determining time of arrival information relating to when a packet data unit was received at the ingress station;

determining latency information relating to an acceptable delay before the egress station should deliver the packet data unit to its destination based on quality of service class information associated with the packet data unit; and

an egress station delivery time for the packet data unit is calculated based on the arrival time information and the latency information.

11. The ingress station of claim 10 wherein the egress station delivery time is determined at least in part by adding latency information to arrival time information of the packet data unit.

12. The ingress station of claim 1 wherein the egress station delivery deadline corresponds to a time.

13. The ingress station of claim 1 wherein the egress station delivery deadline corresponds to a frame for transmission.

14. The ingress station of claim 1 wherein the ingress station is a base station and the egress station is an access relay station supporting wireless communication with at least one user terminal, the at least one user terminal participating in the at least one service flow.

15. The ingress station of claim 1 wherein the egress station is a base station and the ingress station is an access relay station supporting wireless communication with at least one user terminal, the at least one user terminal participating in the at least one service flow.

16. The entry station of claim 1, wherein the control system is further adapted to:

identifying quality of service (QoS) class information associated with a QoS class of a packet data unit; and

the egress station delivery deadline is provided with the packet data unit, wherein the packet data unit is delivered via the tunnel to an intermediate relay station of the one or more relay stations along with the QoS class information and the egress station delivery deadline.

17. An intermediate relay station residing in a wireless communication access path in a wireless communication environment, wherein a tunnel is established between an ingress station and an egress station through the intermediate relay station along the wireless communication access path, the intermediate relay station comprising:

a wireless communication circuit;

receiving a plurality of packet data units associated with at least one service flow supported by a tunnel, wherein each of the plurality of packet data units comprises an egress station delivery deadline by which an egress station should deliver a packet data unit to a destination of the packet data unit before or at the egress station delivery deadline; and is

For each of a plurality of packet data units;

determining an intermediate relay station delivery deadline for the packet data unit, wherein the intermediate relay station should deliver the packet data unit to the egress station on or before the intermediate relay station delivery deadline to ensure that the packet data unit reaches the egress station in sufficient time to be delivered to a destination of the packet data unit before the egress station delivery deadline; and

the packet data unit is delivered to the egress station with the egress station delivery deadline at or before the intermediate relay station delivery deadline.

18. The intermediate relay station of claim 17 wherein the packet data unit is delivered to another intermediate relay station that exists between the intermediate relay station and an egress station.

19. The intermediate relay station of claim 17 wherein the packet data unit is received from another intermediate relay station existing between the intermediate relay station and the ingress station.

20. The intermediate relay station of claim 17 wherein to determine the intermediate relay station delivery deadline for the packet data unit, the control system is further adapted to:

determining propagation information relating to how long it may take a packet data unit to be delivered from the intermediate relay station to the egress station; and

an intermediate relay station delivery deadline is calculated based on the propagation information and the egress station delivery deadline.

21. The intermediate relay station of claim 20 wherein the intermediate relay station delivery time is calculated at least in part by subtracting the propagation information from the egress station delivery deadline.

22. The intermediate relay station of claim 17 wherein the intermediate relay station delivery deadline corresponds to a time.

23. The intermediate relay station of claim 17 wherein the intermediate relay station delivery deadline corresponds to a frame for transmission.

24. The intermediate relay station of claim 17 wherein the ingress station is a base station and the egress station is an access relay station supporting wireless communication with at least one user terminal, the at least one user terminal participating in the at least one service flow.

25. The intermediate relay station of claim 17 wherein the egress station is a base station and the ingress station is an access relay station supporting wireless communication with at least one user terminal, the at least one user terminal participating in the at least one service flow.

26. The intermediate relay station of claim 17 wherein when a number of packet data units of the plurality of packet data units have the same intermediate relay station delivery deadline, quality of service class information associated with the number of packet data units is used to control an order in which the number of packet data units are delivered to the egress station.

27. The intermediate relay station of claim 17 wherein the control system is further adapted to:

determining a propagation metric related to at least one link between the intermediate relay station and the egress station; and

information relating to the propagation metric is delivered to the ingress station.

28. The intermediate relay station of claim 27 wherein the propagation metric for at least one link is delivered to the ingress station in a record having a different field for the propagation metric for each link reported.

29. The intermediate relay station of claim 17 wherein each of the plurality of packet data units includes quality of service (QoS) class information related to a QoS class of the packet data unit and is delivered to the egress station at or before the intermediate relay station delivery deadline along with the QoS class information and the egress station delivery deadline.

30. A method for operating an ingress station present in a wireless communication access path in a wireless communication environment, wherein a tunnel is established between the ingress station and an egress station through at least one intermediate relay station along the wireless communication access path, the method comprising:

for each packet data unit of the plurality of packet data units:

providing an egress station delivery deadline with the packet data unit; and

the packet data unit is delivered to the intermediate relay station via the tunnel with the egress station delivery deadline.

31. The method of claim 30, further comprising:

the egress station delivery deadline is provided with the packet data unit, wherein the packet data unit is delivered to the intermediate relay station via the tunnel with the QoS information and the egress station delivery deadline.

32. The method of claim 30, further comprising determining an ingress station delivery deadline for the packet data unit, wherein the ingress station should deliver the packet data unit to the intermediate relay station at or before the ingress station delivery deadline to ensure that the packet data unit reaches the egress station in sufficient time to be delivered to the destination of the packet data unit before the egress station delivery deadline, and wherein the packet data unit is delivered to the intermediate relay station at or before the ingress station delivery time.