HK1140618A - Restrictive reuse for a wireless communication system - Google Patents

Description

Restrictive reuse for wireless communication systems

The present application is a divisional application of application 200480039573.X entitled "restrictive reuse of wireless communication system" filed on 10/28/2004.

Priority requirements according to 35U.S.C. § 119

This application claims priority from U.S. provisional patent application serial No.60/516,558, filed 10/30/2003, assigned to the assignee of the present application and incorporated herein by reference.

Technical Field

The present invention relates generally to communications, and more particularly to data transmission in a wireless multiple-access (multiple-access) communication system.

Background

A wireless multiple-access system is capable of supporting communication for multiple wireless terminals on the forward and reverse links simultaneously. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. Multiple terminals may transmit data on the reverse link and/or receive data on the forward link simultaneously. This may be accomplished by multiplexing together multiple data transmissions on each link that are orthogonal to each other in the time, frequency, and/or code domain. Orthogonality ensures that the data transmission of each terminal does not interfere with the data transmission of other terminals.

Multiple access systems typically have many cells, where the term "cell" can refer to a base station and/or its coverage area depending on the context in which the term is used. Data transmissions for terminals within the same cell may be sent using orthogonal multiplexing to avoid "intra-cell" interference. However, the data transmissions for terminals within different cells may not be orthogonal, in which case each terminal may observe "inter-cell" interference from other cells. For some disadvantaged terminals observing strong interference, the inter-cell interference may significantly reduce its performance.

To overcome inter-cell interference, wireless systems may employ frequency reuse schemes such that not all frequency bands available in the system are used in each cell. For example, the system may employ a 7-cell reuse pattern with a reuse factor K of 7. For this system, the overall system bandwidth W is divided into seven equal frequency bands, with each cell in a 7-cell cluster being assigned one of the 7 frequency bands. Each cell uses only one frequency band and the same frequency band is reused every seven cells. With this frequency reuse scheme, the same frequency band is reused only in cells that are not adjacent to each other, which allows the inter-cell interference observed in each cell to be reduced compared to the case where all cells use the same frequency band. However, since each cell can only use a portion of the total system bandwidth, a large reuse factor (e.g., two or more) represents a less efficient use of the available system resources.

Accordingly, there is a need in the art for techniques that can reduce inter-cell interference in a more efficient manner.

Disclosure of Invention

In the following, techniques for effectively avoiding or reducing interference from strong interferers in a wireless communication system will be described. The strong interferer for a given user u may be a base station (on the forward link) or another user (on the reverse link). User u may also be a strong interferer to other users. A strong interfering entity for user u may be a strong interferer causing strong interference to user u and/or an interfered party observing strong interference from or due to user u. The strong interfering entity (or interferer/interferer, reduced to interferer/interferer) for each user may be identified as described below. Users are assigned system resources (e.g., subbands) that are orthogonal to the system resources used by the strong interferers/victims of those users to avoid interference with another party. These techniques are referred to as "restrictive reuse" techniques and may be used for a variety of wireless systems and for the forward and reverse links.

In an embodiment of restrictive reuse, each cell/sector is assigned (1) a set of usable subbands that may be allocated to users in that cell/sector and (2) a set of forbidden subbands that may not be allocated to users in that cell/sector. The usable and forbidden sets for each cell/sector are orthogonal to each other. The usable set of each cell/sector also overlaps the forbidden set of each neighboring cell/sector. A given user u in a cell/sector x may be assigned multiple subbands in the cell/sector's available set. If user u observes (or causes) high-strength interference from neighboring cell/sector y, then user u may be assigned subbands from a "restricted" set that contains subbands included in both the available set for cell/sector x and the forbidden set for cell/sector y. Then user u will not observe interference from (or cause interference to) cell/sector y since the subband assigned to user u is a member of the forbidden set that is not used by cell/sector y. This subband restriction may be extended to avoid interference from multiple neighboring cells/sectors.

Various aspects and embodiments of the invention are described in more detail below.

Drawings

The features and nature of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like parts are given like reference numerals throughout the drawings and wherein:

fig. 1 illustrates a wireless multiple-access communication system;

FIGS. 2A and 2B illustrate a sectorized cell and its model, respectively;

FIG. 3 shows an exemplary multi-cell layout of a cell having three sectors;

FIG. 4 shows three overlapping forbidden sets of three sectors;

FIGS. 5A through 5D illustrate four non-restricted and restricted sets of a sector;

FIG. 6 shows an example of forming three forbidden subband sets;

figures 7A to 7D show the distribution of four users in a cluster of 7 sectors and a non-interference pattern for three of them;

FIG. 8 shows a flow for allocating subbands to users with restrictive reuse;

fig. 9 shows a block diagram of a transmitting entity; and

fig. 10 shows a block diagram of a receiving entity.

Detailed Description

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

Fig. 1 illustrates a wireless multiple-access communication system 100. System 100 includes a plurality of base stations 110 that support communication with a plurality of wireless terminals 120. A base station is a fixed station used for communicating with the terminals and may also be referred to as an access point, a node B, or some other terminology. Terminals 120 are typically dispersed throughout the system, and each terminal may be fixed or mobile. A terminal may also be called a mobile station, User Equipment (UE), a wireless communication device, or some other terminology. Each terminal may communicate with one or possibly more base stations on the forward and reverse links at any given moment.

For a centralized architecture, a system controller 130 couples to and provides coordination and control for the base stations. For a distributed architecture, a base station may communicate with another base station as needed (e.g., to provide services to terminals), coordinate use of system resources, and so on.

Fig. 2A shows a cell 210 having three sectors. Each base station provides communication coverage for a respective geographic area. The coverage area for each base station may be any size and shape, and is typically dependent on a variety of factors, such as terrain, obstructions, and the like. To increase capacity, the base station coverage area may be divided into three sectors 212a, 212b, and 212c, labeled as sectors 1, 2, and 3, respectively. Each sector may be defined by a respective antenna beam pattern (beampattern), and the three beam patterns of the three sectors may point in directions that are 120 ° apart from each other. The size and shape of each sector is typically dependent on the antenna beam pattern of that sector, and the sectors of a cell typically overlap at the edges. A cell/sector may be a non-adjacent area and the edge of a cell/sector may be quite complex.

Fig. 2B shows a simple model of a sectorized cell 210. The model for each of the three sectors in cell 210 is constructed as an ideal hexagon close to the sector boundary. The coverage area of each base station may be represented by a clover of three ideal hexagons centered at the base station.

Each sector is typically served by a Base Transceiver Subsystem (BTS). In general, the term "sector" may refer to a BTS and/or its coverage area, depending on the context in which the term is used. For a sectorized cell, the base station of the cell typically contains BTSs for all sectors of the cell. For simplicity, in the following description, the term "base station" is used generically for a fixed station that serves a cell and a fixed station that serves a sector. A "serving" base station or "serving" sector refers to a base station or sector that communicates with the terminals. The terms "terminal" and "user" may also be used interchangeably herein.

Restrictive reuse techniques may be used in a variety of communication systems. For clarity, these techniques are each described for an Orthogonal Frequency Division Multiple Access (OFDMA) system utilizing Orthogonal Frequency Division Multiplexing (OFDM). OFDM effectively partitions the overall system bandwidth into multiple (N) orthogonal frequency subbands, also known as tones (tones), subcarriers, bins (bins), frequency channels, and so on. Each subband is associated with a respective subcarrier that may be modulated with data.

In an OFDMA system, multiple orthogonal "traffic" channels may be defined such that (1) each subband is used by only one traffic channel in any given time interval, and (2) each traffic channel may be assigned zero, one, or multiple subbands in each time interval. A traffic channel may be considered as a convenient way to represent subband assignments for different time intervals. Each terminal may be assigned a different traffic channel. For each sector, multiple data transmissions may be sent simultaneously on multiple traffic channels without interfering with each other.

The OFDMA system may or may not use Frequency Hopping (FH). With frequency hopping, the data transmission hops from sub-band to sub-band in a pseudo-random manner, which can provide frequency diversity and other advantages. For a frequency hopping OFDMA (FH-OFDMA) system, each traffic channel may be associated with a particular FH sequence that represents the specific subband to use for that traffic channel in each time interval (or hop period). The FH sequences for different traffic channels in each sector are orthogonal to each other so that no two traffic channels use the same subband in any given hop period. The FH sequence for each sector may also be pseudo-random with respect to the FH sequences for neighboring sectors. These characteristics of the FH sequences minimize intra-sector interference and randomize inter-sector interference.

In an OFDMA system, users with different channel conditions may be distributed throughout the system. These users may have different impact and inter-sector interference margins. The channel condition for each user may be quantified by a signal quality metric defined by a signal-to-interference-and-noise ratio (SINR), a channel gain, a received pilot power, and/or some other quantity that may be measured for the user's serving base station, some other measurement, or any combination thereof. A weak user has a relatively poor signal quality metric (e.g., a low SINR) for its serving base station, for example, due to low channel gain and/or strong inter-sector interference for its serving base station. The weak user may generally be anywhere within the sector, but is generally remote from the serving base station. In general, weak users are less tolerant of inter-sector interference, and also cause more interference to users in other sectors, which have poor performance and can become a bottleneck in systems that enforce fairness requirements.

Restrictive reuse can avoid or reduce interference observed by weak users (observe)/caused. This may be accomplished by determining a likely strong inter-sector interference source (or strong interferer) and/or a likely victim of strong inter-sector interference (or strong interferer) for a weak user. A strong interferer may be a base station (on the forward link) and/or a user (on the reverse link) in a neighboring sector. A strong interferer may be a user in an adjacent sector. In any case, the subbands assigned to the weak users should be orthogonal to the subbands used by the strong interferers/strong interferers.

In an embodiment for restrictive reuse, each sector x is assigned a set of available subbands (denoted as U)_x) And a forbidden or unused set of subbands (denoted as F)_x). The available set contains subbands that are assigned to users in the sector. The forbidden set contains subbands that are not assigned to users in the sector. The usable and forbidden sets for each sector are orthogonal or disjoint, i.e., do not include any identical subbands in both sets. The usable set of each sector also overlaps the forbidden sets of respective neighboring sectors. Forbidden sets of multiple adjacent sectors may also be interleavedAnd (5) stacking. The users in each sector may be assigned subbands in the available set, as described below.

Restrictive reuse may be used for systems consisting of cells that are not sectorized, as well as systems consisting of sectorized cells. For clarity, restrictive reuse is described below with a system of 3-sector cell composition as an example.

Fig. 3 shows an exemplary multi-cell layout 300, with each 3-sector cell modeled as a clover of three hexagons. For this cell layout, each sector is surrounded in the first ring (or first ring) by a number of sectors that are marked differently from the sector. Thus, each sector 1 is surrounded by six sectors 2 and 3 in the first layer, each sector 2 is surrounded by six sectors 1 and 3, and each sector 3 is surrounded by six sectors 1 and 2.

FIG. 4 shows a Venturi (Venn) diagram depicting the formation of three overlapping subband sets, labeled F₁，F₂And F₃They can be used as three forbidden subband sets. In this example, each forbidden set overlaps each of the other two forbidden sets (e.g., forbidden set F)₁And forbidden set F₂And F₃Each of which overlap). Because of this overlap, an intersection operation on any two forbidden sets generates a non-empty set. This property can be expressed in the form:

F₁₂＝F₁∩F₂≠Θ，F₁₃＝F₁∩F₃not equal to Θ and F₂₃＝F₂∩F₃Not theta, formula (1) wherein "n" represents an intersection operation;

F_xyto include a set F_xAnd F_yA set of common subbands; and

Θ represents an invalid/empty set.

These three forbidden sets F₁，F₂And F₃Each of which is a subset of the full set omega, wherein the full setOmega contains a total of N subbands, i.e.,andto make efficient use of the available subbands, the three forbidden sets may be defined such that none of the three sets overlap, which may be expressed as:

F₁₂₃＝F₁∩F₂∩F₃Θ formula (2)

The conditions in equation (2) ensure that each subband is used by at least one sector.

Based on these three forbidden subband sets F₁，F₂And F₃Three usable subband sets U may be formed separately₁，U₂And U₃. Each available set U_xCan pass through the full set omega and the forbidden set F_xThe difference set of (2) is formed as follows:

U₁＝Ω\F₁，U₂＝Ω\F₂and U₃＝Ω\F₃Equation (3)

Wherein "\\" represents a difference set operation; and

U_xis not included in the set F_xThe set of subbands in the full set Ω.

The three sectors in each 3-sector cell are assigned different pairs of usable and forbidden sets. For example, set U will be available₁And disable set F₁Assign to sector 1, set available U₂And disable set F₂Assigned to sector 2, the available set U₃And disable set F₃Assigned to fanZone 3. Each sector may also have knowledge of the forbidden sets assigned to neighboring sectors. In this way, sector 1 can learn the forbidden set F assigned to neighboring sectors 2 and 3₂And F₃Sector 2 may have knowledge of the forbidden set F assigned to neighboring sectors 1 and 3₁And F₃Sector 3 may learn the forbidden set F assigned to neighboring sectors 1 and 2₁And F₂。

FIG. 5A shows an available set U assigned to sector 1₁The venturi diagram of (a). Usable set U₁(as indicated by the diagonal lines) comprising a forbidden set F of a total of N subbands₁All subbands other than those contained in (c).

FIG. 5B illustrates a restricted available set U of sector 1_1-2(as shown by the cross-hatched area). Restricted set U_1-2Including usable set U included in sector 1₁And a forbidden set F included in sector 2₂Of (2). Due to disabling set F₂Is unused by sector 2 and is therefore in restricted set U_1-2The subbands in (a) are not subject to interference from sector 2.

FIG. 5C shows a restricted available set U of sector 1_1-3(as indicated by the vertical line regions). Restricted set U_1-3Including usable set U included in sector 1₁And a forbidden set F included in sector 3₃Of (2). Due to disabling set F₃Is unused by sector 3 and is therefore in restricted set U_1-3The subbands in (a) are not subject to interference from sector 3.

FIG. 5D shows a larger restricted available set U for sector 1_1-23(as shown in the solid fill zone). Restricted set U_1-23Including usable set U in sector 1₁Forbidden set of sectors 2F₂And sector 3 forbidden set F₃The subbands included in all three sets. Due to disabling set F₂And F₃Are unused by sectors 2 and 3 and are therefore in restricted set U_1-23The subbands in (a) are not subject to interference from sectors 2 and 3.

As shown in FIGS. 5A-5D, the restricted available set U_1-2，U_1-3，U_1-23Unrestricted available set U assigned to sector 1₁Different subsets of (a). In the same way, a restricted usable set U of sectors 2 can be formed_2-1，U_2-3，U_2-13And forming a restricted usable set U of sectors 3_3-1，U_3-2，U_3-12. Table 1 lists the various usable subband sets for these three sectors, and the manner in which these sets are formed. The "reuse" set in table 1 is shown below.

TABLE 1

Each sector x (where x is 1, 2, or 3) may have its available set U by considering the channel conditions of the users_xThe subbands in (a) are assigned to users in a sector to achieve better performance for all users. Sector x may have weak users and strong users. Strong users have relatively better signal quality metrics for their serving base stations and are generally more tolerant of higher strength inter-sector interference. Weak users can tolerate little inter-sector interference. Sector x can aggregate it with its available set U_xAny subband in (a) is assigned to a strong user in the sector. Sector x may assign subbands in the restricted set to weak users in the sector. In this way, weak users may be effectively limited to those subbands that are known not to be interfered with from the strong interfering sector.

For example, the available set U of sectors x may be set_xThe subbands in (a) are assigned to a given user u in sector x. If user U is deemed to observe/result in strong inter-sector interference from/to sector y, where y ≠ x, then the restricted set U can be_x-y＝U_x∩F_yIs allocated to user u. If further deemed user u will observe from sectorz, where z ≠ x and z ≠ y, then from a larger restricted set U_x-yz＝U_x∩F_y∩F_zIs allocated to user u.

FIG. 6 illustrates the formation of three forbidden subband sets F₁，F₂And F₃Examples of (3). In this example, the total N subbands are divided into Q groups, each group containing 3L subbands, numbered from 1 to 3L, where Q ≧ 1 and L > 1. Forbidden set F₁Containing subbands 1, L +1 and 2L +1 in each group. Forbidden set F₂Containing subbands 1, L +2 and 2L +2 in each group. Forbidden set F₃Containing subbands 2, L +1 and 2L +2 in each group. Thus, set F₁₂Containing sub-bands 1 in groups, set F₁₃Including subbands L +1 in each group, and set F₂₃Containing subband 2L +2 in each group.

In general, each forbidden set may contain any of an arbitrary number of subbands and N total subbands subject to the constraints shown in equation (1) and possibly also subject to equation (2). To achieve frequency diversity, each forbidden set may contain subbands taken from a total of N subbands. The subbands in each forbidden set may be distributed based on a predetermined pattern among the N total subbands, as shown in fig. 6. Alternatively, the subbands in each forbidden set may be randomly distributed across the total of N subbands. These three forbidden sets F₁，F₂And F₃And may also be defined as having any amount of overlap. The amount of overlap may depend on a variety of factors, such as the efficient reuse factor required for each sector (described below), the expected number of weak users in each sector, and so on. The three forbidden sets may overlap each other by the same amount, as shown in fig. 4, or may also overlap by different amounts.

Each user may be associated with a "reuse" set that includes the user's serving sector and the user's strong interferers/strong interferers (if any). The serving sector is represented in the reuse set by bold and underlined text. Strong dryThe interferer/strong interferer is represented by plain text in the reuse set and is behind the bold and underlined text of the serving sector. For example, reuse set (21, 3) indicates that sector 2 is the serving sector and sectors 1 and 3 are strong interferers/strong interferers.

The strong interferer for a given user u on the forward link is typically fixed and the pilot transmitted, e.g., on a sector basis, can be unambiguously identified. For example, forward link measurements performed by user u may not readily identify a strong interferer on the reverse link to user u, but may be inferred based on, for example, reverse link interference measurements performed by user u's serving base station. Strong interferers to user u may also be explicitly identified or inferred. The strong interferer/strong interferer for each user may be determined in a number of ways.

In one embodiment, the strong interferer/strong interferer for a given user u may be determined based on the received pilot power measured by user u for different sectors. Each sector may transmit pilot on the forward link for various purposes such as signal detection, timing and frequency synchronization, channel estimation, and so on. User u may search for pilots transmitted by the sector and measure the received power of each detected pilot. User u may then compare the received pilot power for each detected sector to a power threshold and add the sector to its reuse set if the received pilot power for the sector exceeds the power threshold.

In another embodiment, the strong interferer/strong interferer is determined for user u based on the "active" set maintained by user u. The active set contains all candidate sectors serving user u. For example, a sector may be added to the active set if its received pilot power, as measured by user u, exceeds an add threshold (which may or may not be equal to the power threshold). Each user in the system needs to update (e.g., periodically) its active set and report the active set to its serving sector. Active set information is obviously available at the sector and can be used for restrictive reuse.

In yet another embodiment, a strong interferer/strong interferer can be determined for user u based on received pilot powers measured at different sectors for user u. Each user may also transmit a pilot on the reverse link for various purposes. Each sector may search the system for pilots transmitted by users and measure the received power of each detected pilot. Each sector may then compare the received pilot power for each detected user to a power threshold and notify the serving sector of the user if the received pilot power exceeds the power threshold. The serving sector for each user may then add the sector that has reported the higher received pilot power to the reuse set for that user.

In yet another embodiment, a strong interferer/strong interferer for user u may be determined based on the location estimate for user u. Estimating the location of user u may be for various reasons (e.g., to provide location services to user u) and may utilize various location determination techniques (e.g., Global Positioning System (GPS), advanced forward link trilateration (a-FLT), etc., as is well known in the art). Then, based on the location estimate of user u and the layout information of the sectors/cells, the strong interferer/strong interferer for user u may be determined.

Several embodiments for determining a strong interferer/strong interferer per user are described above. The strong interferer/strong interferer may also be determined in other manners and/or based on other quantities in addition to the received pilot power. A better signal quality metric for determining strong interferers on the forward link is the average SINR measured at the user of the base station, which is also referred to as "geometry". Since SINR measurements cannot be made at the user of the base station, a better signal quality metric for determining a strongly interfered party on the reverse link is the channel gain measured at the user of the base station. A single reuse set may be maintained for the forward and reverse links or separate sets may be used for both links. The same or different signal quality metrics may be used to update each sector in the reuse set for the forward and reverse links.

In general, strong interferers/strong interferers may be explicitly identified based on direct measurements (e.g., for the forward link) or inferred based on relative measurements, sector/cell layout, and/or other information (e.g., for the reverse link). For simplicity, the following description assumes that each user is associated with a single reuse set that includes the serving sector and other sectors (if any) that are deemed to be strong interferers/strong interferers to that user.

In a well-designed system, a weak user should have a relatively fair signal quality metric for at least one neighboring sector. This allows weak users to be handed off from the current serving sector to the neighboring sector when necessary. Each such neighboring sector may be identified as a strong interferer/strong interferer to the weak user and may be included in the reuse set of users.

Fig. 7A shows an example distribution of four users in a 7 sector cluster. In this example, user 1 is in a position near the middle of sector 1 and has a reuse set of (a)1). User 2 is located close to the boundary between sectors 1 and 3 and has a reuse set(s) ((1,3). User 3 is also located close to the boundary between sectors 1 and 3, but with reuse set (c) ((c))3,1). User 4 is located near the boundaries of sectors 1, 2, and 3 with reuse set(s) ((ii))1，2，3)。

Fig. 7B illustrates a non-interference mode of the user 1 in fig. 7A. Since the reuse set of user 1 is (1) Thus, the available set U will be available₁Is allocated to user 1. Since users in sector 1 are assigned orthogonal subbands, user 1 does not interfere with other users in sector 1. However, the available set U₁Not the available set U with sectors 2 and 3, respectively₂And U₃Are orthogonal. Thus, user 1 may observe interference from six neighboring sectors 2 and 3 in the first turn around sector 1. User 1 may typically observe interference from distant or weak interferers in the six neighboring sectors, as a result ofStrong interferers in these neighboring sectors (for sector 1/user 1) are assigned with the available set U₁Of (e.g., in the restricted set U)_2-1And U_3-1Sub-band(s) in (c). The area where other users do not interfere with user 1 is shown by the cross-hatching, which covers sector 1 and the edges of other sectors adjacent to sector 1 (since users in these adjacent sectors 2 and 3 are assigned subbands not used by sector 1).

Fig. 7C shows the interference-free mode of user 2 in fig. 7A. Since the reuse set of user 2 is (13), and thus will restrict the set U_1-3＝U₁∩F₃Is allocated to user 2. Since sector 3 does not use its forbidden set F₃And thus the subband assigned to user 2 is orthogonal to the subband used by sector 3. Thus, user 2 does not observe any interference from other users in sector 1 as well as users in sector 3. User 2 may observe interference from distant interferers in the three first-turn neighbor sectors 2. The area where other users do not interfere with user 2 covers sectors 1 and 3 and the edge of sector 2 adjacent to sector 1 (for the reasons described above with respect to fig. 7B).

Fig. 7D illustrates a non-interference mode of user 4 in fig. 7A. Since the reuse set for user 4 is (1, 2, 3), the restricted set U will be_1-23＝U₁∩F₂∩F₃Is allocated to user 4. Since sectors 2 and 3 do not use their respective forbidden sets F₂，F₃And thus the subband assigned to user 4 is orthogonal to the subbands used by sectors 2 and 3. Thus, user 4 does not observe interference from other users in sector 1 and users in the six first-turn neighboring sectors 2 and 3. The area where other users do not interfere with user 4 covers sectors 1, 2, and 3.

In fig. 7A, users 2 and 3 are located very close to each other and will interfere strongly with each other without restrictive reuse. With restrictive reuse, the reuse set for user 2 is13), and thus will restrict the set U_1-3＝U₁∩F₃Is allocated to user 2, since the reuse set of user 3 is (31), and thus will restrict the set U_3-1＝U₃∩F₁Is allocated to user 3. Since each restricted set U_x-yIncluding only the divisible sets U_yOther sub-bands, and, moreover, another restricted set U_y-xIs U_yThus, a restricted set U_1-3，U_3-1Are orthogonal to each other. Due to the fact that the signal is from an orthogonal limited set U_1-3And U_3-1Are assigned to users 2 and 3, respectively, which do not interfere with each other.

As shown in fig. 7A-7D, as the size of the user reuse set increases, the interference experienced by the user decreases. Users with a reuse set size of one (e.g., user 1 in fig. 7B) are interfered by distant interferers in the six first-turn neighboring sectors. Users with a reuse set size of two (e.g., user 2 in fig. 7C) are interfered by distant interferers in the three first-turn neighboring sectors. Users with a reuse set size of three are interfered by an interferer in a second circle of adjacent sectors. In contrast, without restrictive reuse, all users in the system will experience interference from randomly distributed interferers in all six first-turn neighbor sectors.

Restrictive reuse may be used to mitigate inter-sector interference for weak users on the forward and reverse links. On the forward link, a weak user u in sector x may observe strong inter-sector interference from base stations in neighboring sectors in its reuse set. The weak users u may be assigned subbands unused by these neighboring sectors so that the weak users u will not observe interference from these sector base stations. Thus, restrictive reuse may directly improve the SINR for each weak user u.

On the reverse link, a weak user u may observe strong inter-sector interference from users in neighboring sectors in its reuse set. The weak user u may be assigned subbands unused by these neighboring sectors so that the weak user u will not observe interference from users in these sectors. Weak user u may also become a strong interferer to users in neighboring sectors. The weak user u typically transmits at a high power level in order to increase its received SINR at its serving sector x. This high transmit power results in more severe interference to all users in the adjacent sector. By restricting weak user u to use only subbands that are unused by neighboring sectors in the reuse set, weak user u will not cause interference to users in these sectors.

When restrictive reuse is applied across the entire system, a weak user u may benefit from lower inter-sector interference on the reverse link even if a strong interferer to the weak user u cannot be identified. A weak user in an adjacent sector with sector x in its reuse set may become a strong interferer to weak user u in sector x as well as other users. These strong interferers may be assigned subbands that are not used by sector x so that they will not cause interference to users in sector x. Thus, even if user u cannot identify these strong interferers, user u will not observe inter-sector interference from these strong interferers. Restrictive reuse will typically increase the SINR for all weak users.

For both the forward and reverse links, restrictive reuse can avoid or reduce interference from strong interferers observed by weak users, which can improve SINR for the weak users. Restrictive reuse may reduce the amount of SINR variation among users in the system. Thus, improved communication coverage and higher overall system capacity can be achieved for the system.

Fig. 8 shows a flow diagram of a process 800 for allocating subbands to users in a sector through restrictive reuse. Process 800 may be performed by or for each sector. Initially, a strong "interfering entity" is identified for each user in the sector (if present) (block 812). For a given user u, the strong interfering entity may be (1) a strong interferer that causes strong interference to user u, and/or (2) a strong interferer that is able to observe strong interference from or caused by user u. Thus, the strong interfering entity for user u may be (1) causing strong interference to user u on the forward linkA base station that is interfering, (2) another user that is causing strong interference to user u on the reverse link, (3) a base station that can observe strong interference from user u on the reverse link, (4) another user that can observe strong interference from user u's serving base station on the forward link, or (5) some other entity that seeks to mitigate interference with user u. For example, a strong interfering entity may be identified based on received pilot power measured by a user for different sectors, or received pilot power measured by different sectors for a user, and so on. The strong interfering entity for each user may be included in the reuse set for the user, as described above. In any case, a restricted available set may be determined for each user with at least one strong interfering entity (block 814). By performing an intersection operation, i.e., U, of the available set of user serving sectors with the forbidden set of each strong interfering entity_x-y...＝U_x∩F_y.., a restricted set for each user may be obtained. For each user with at least one strong interfering entity, the subbands in the restricted set determined for the user may be allocated to the user (block 816). For each user that does not have a strong interfering entity, the remaining subbands in the sector's available set may be allocated to that user (block 818). The process then ends.

Process 800 shows first allocating subbands to a weak user with at least one strong interfering entity and then allocating remaining subbands to a strong user. In general, the subbands may be allocated to the weak and strong users in any order. For example, the subbands may be assigned to users based on their priorities, which may be determined by a number of factors, such as the SINR achieved by the user, the data rate supported by the user, the payload size, the type of data to be transmitted, the amount of delay the user has experienced, the outage (outage) probability, the maximum available transmit power, the type of data service being provided, etc. These various factors may be given appropriate weights and used to prioritize the various users. The users are then assigned subbands based on their priorities.

Process 800 may be performed by each sector in each scheduling interval, which may be a predetermined time interval. Each sector may send signaling (e.g., users that assign different subbands to all users or only some users) indicating the subbands assigned to each user. (1) Process 800 may be performed whenever a user in a sector changes (e.g., if a new user is added, or a current user is removed), (2) whenever a user's channel conditions change (e.g., whenever a user's reuse set changes), or (3) at any time and/or due to any triggering criteria. Not all subbands may be used for scheduling at any given moment, e.g., some subbands may have been used for retransmission or for some other purpose.

The forbidden set represents an overhead (overhead) that supports restrictive reuse. Due to being in the disabled set F_xThe subbands in (a) are not used by sector x, and the percentage of subbands usable by sector x to the total (i.e., the effective reuse factor for sector x) may be expressed as follows: i U_x|/|Ω|＝(|Ω|-|F_x|)/| Ω |, where | U_xI means set U_xThe size of (2). In order to reduce the overhead amount of restrictive reuse, the forbidden set may be defined as small as possible. However, the size of the restricted set depends on the size of the forbidden set. Thus, the forbidden set may be defined based on the expected requirements of the weak user and possibly other factors.

The available and disabled sets may be defined in various ways. In one embodiment, the available and disabled sets are defined based on the full frequency plan of the system and remain static. Each sector is assigned an available set and a disabled set, forming its restricted set as described above, and then uses the available and restricted sets. This embodiment simplifies the implementation of restrictive reuse since each sector can be performed autonomously and without signaling communication between adjacent sectors. In a second embodiment, the available and disabled sets may be dynamically defined based on sector loading (loading) and possibly other factors. For example, the forbidden set for each sector may depend on the number of weak users in neighboring sectors that varies over time. A designated sector or system entity (e.g., system controller 130) may receive loading information for a plurality of different sectors, define available and disabled sets, and assign the sets to the sectors. This embodiment enables a better utilization of system resources based on user distribution. In another embodiment, a sector may send an inter-sector message to negotiate the available and disabled sets.

Restrictive reuse can support handover, which is the transfer of a user from a currently serving base station to another base station that is deemed better. Performing a handoff as needed may enable users on the edge of sector coverage (or "sector-edge" users) to maintain good channel conditions. Some conventional systems, such as Time Division Multiple Access (TDMA) systems, support "hard" handovers, in which a user first leaves the current serving base station and then switches to a new serving base station. Code Division Multiple Access (CDMA) systems support "soft" and "softer" handoffs, which enable users to communicate with multiple cells (for soft handoffs) or multiple sectors (for softer handoffs) simultaneously. Soft and softer handoff can further mitigate fast fading.

Restrictive reuse can reduce interference for sector-edge users, which are better candidates for handoff. Restrictive reuse can also support hard, soft, and softer handoffs. Will be limited to set U_x-yThe subbands in (a) are assigned to sector-edge user u in sector x so that sector-edge user u does not interfere with neighboring sector y. Sector-edge users U may also pass through a restricted set U_y-xThe subbands in (a) communicate with sector y so that no interference occurs with sector x. Due to limited set U_x-yAnd U_y-xDisjoint, user u can communicate with sectors x and y simultaneously (without interfering with strong interferers in both sectors) for soft or softer handoff. User u may also perform a hard handoff from sector x to sector y. Due to limited set U_x-yAnd U_y-xThere are no strong interferers from sectors y and x each, so that when a user switches from sector x to sector y, the received SINR for user u does not change dramatically, which provides for a smooth handoff.

Power control may or may not be used in conjunction with restrictive reuse. The power control adjusts the transmit power of the data transmission such that the received SINR of the transmission remains at the target SINR, which in turn may be adjusted to achieve a particular level of performance, e.g., 1% Packet Error Rate (PER). Power control may be used to adjust the amount of transmit power for a given data rate in order to minimize interference. Power control is used for some (e.g., fixed rate) transmissions while ignoring other (e.g., variable rate) transmissions. Full transmit power may be used for variable rate transmissions (e.g., hybrid automatic repeat request (H-ARQ), i.e., additional redundant information is continuously transmitted for each packet until the packet is decoded correctly) in order to achieve the highest rate possible for a given channel condition.

In the above embodiment of restrictive reuse, each sector is associated with one usable set and one forbidden set. Some other embodiments of restrictive reuse are described below.

In another embodiment of restrictive reuse, each sector x is assigned an unrestricted usable subband set U_xAnd a "restricted use" subband set L_x. The non-restricted available set contains subbands that may be assigned to any user in the sector. The restricted-use set includes subbands with a particular use limit (e.g., a lower transmit power limit). Set U_xAnd L_xCan be respectively according to the above set U_xAnd F_xIn a manner described above.

Each sector x may be paired to a set U by taking into account the channel conditions of the users_xAnd L_xThe sub-bands in (b) are allocated so that all users achieve better performance. Set U_xThe subbands in (a) may be assigned to any user in sector x. The subbands assigned to the weak users in sector x may be subbands from the following set: (1) if strong interference from neighboring sector y is observed, then it is the restricted set U_x-y＝U_x∩L_yAnd (2) a restricted set U if strong interference from a neighboring sector z is observed_x-z＝U_x∩L_zOr (3) is asIf strong interference from neighboring sectors y and z is observed, then the restricted set U_x-yz＝U_x∩L_y∩L_z. The strong users in sector x may be assigned L_xOf (2).

A strong user v in sector x has a good signal quality metric for its serving sector x and can be assigned to restrict the use of set L_xOf (2). On the forward link, sector x may be in set L_xLower power limit or a power below the lower power limit to transmit to a strong user v. On the reverse link, a strong user v may transmit to serving sector x at or below the lower power limit. Since strong user v of sector x achieves a good signal quality metric, good performance of strong user v can be achieved on both the forward and reverse links even with lower transmit power.

Strong users v typically have a poor signal quality metric for neighboring sectors. On the forward link, the lower transmit power used by sector x for strong user v results in a lower level of interference (and typically tolerable) to users in neighboring sectors. On the reverse link, the lower transmit power used by strong user v plus the lower channel gain of the neighboring sector results in a lower level of interference (and typically tolerable) to the neighboring sector user.

In another embodiment of restrictive reuse, each reuse set is associated with an ordered list of subband sets available to the reuse set. Due to the limitations of frequency planning, the bandwidth of some restricted sets may be very small, e.g., corresponding to the reuse set: (b)12, 3) restricted set U_1-23. Suppose user u observes strong interference from sectors 2 and 3 and is assigned to reuse set: (1,2,3). Although user U may obtain a higher SINR due to interference reduction, it is limited to a smaller limited set U_1-23The resulting loss of bandwidth will still be detrimental to the throughput achievable by user u. Thus, for reuse set: (12, 3) may define a set of subbands with decreasing priorityA combined ordered list, e.g., (U)_1-23，[U_1-2，U_1-3]，U₁) Wherein the subband sets within square brackets have the same priority. Then, if necessary, reuse set(s) (ii)12, 3) may use more bandwidth, which may be achieved by using and reusing the set (2, 3)12, 3) additional subband sets in the associated ordered list. For reuse set (C:)1And 2) the user in (1), the sorted list may be (U)_1-2，U₁，U_1-3，U_1-23). For reuse set (C:)1) For a user in (1), the sorted list may be (U)₁，[U_1-2，U_1-3]，U_1-23). The ordered list for each reuse set may be defined to be capable of (1) reducing the amount of interference observed by users in the reuse set and/or (2) reducing the amount of interference caused by users in the reuse set.

In another embodiment of restrictive reuse, each sector x is assigned multiple (M) available sets and multiple (e.g., M) forbidden sets. The number of usable sets may or may not be equal to the number of forbidden sets. For example, a plurality (M) of pairs of usable and forbidden sets may be formed, where the usable set U in each pair is assigned to_xAnd disable set F_xIs formed in such a way that each subband of the total N subbands is included in the set U only_xOr set F_xIn (1), for example, Ω ═ U_x∪F_xWherein "U" represents a union operation. However, in general, the M usable sets and the M forbidden sets may be formed in a variety of ways.

For example, the M available sets may be formed such that they become a contiguous smaller subset of the maximum available set. Each sector may then use the smallest possible available set based on its loading. This may reduce the overall interference to neighboring sectors when a sector is partially loaded. This may also increase the amount of interference observed by neighboring sectors, which may thus be used to improve overall system performance.

The M disabled sets may be formed such that they do not overlap each other. The number of weak users in each sector and their data requirements are generally not predictable. The number of forbidden sets of neighboring sectors utilized by each sector may be the same as the number of forbidden sets needed to support its weak users. For example, sector x may use subbands in more of the forbidden sets for sector y to provide a higher data rate or to support more of one or more weak users in sector x that can observe strong interference from sector y. Each sector may coordinate utilization of the forbidden set.

In general, each sector may be assigned any number of non-restricted usable subband sets and any number of "constrained" subband sets. The constrained subband set may be a forbidden subband set or a restricted use subband set. For example, a sector may be assigned multiple restricted subband sets. One constrained subband set may be a forbidden subband set, and the remaining constrained subband sets may have different transmit power limits and may be assigned to different rings of strong users. For another example, a sector can be assigned multiple restricted subband sets, where each restricted subband set can have a different transmit power limit (i.e., no forbidden set). Using multiple available and/or restricted sets per sector may allow for better subband matching for weak users in different sectors.

For clarity, restrictive reuse has been described with particular reference to a system having a three sector cell. In general, restrictive reuse may be used for any reuse pattern. For a K sector/cell reuse pattern, the forbidden set for each sector/cell can be defined such that it overlaps with the forbidden sets for each of the other K-1 sectors/cells, and can overlap with different combinations of the other forbidden sets. Each sector/cell may form different restricted sets for different neighboring sectors based on its available set and the forbidden set of neighboring sectors. Each sector/cell may then use the available and restricted set described above.

Restrictive reuse has been described for OFDMA systems. In addition, restrictive reuse may also be used in TDMA systems, Frequency Division Multiple Access (FDMA) systems, CDMA systems, multi-carrier CDMA systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, and the like. TDMA systems use Time Division Multiplexing (TDM) to make the transmissions of different users orthogonal to each other by transmitting in different time intervals. FDMA systems use Frequency Division Multiplexing (FDM) to orthogonalize the transmissions of different users by transmitting in different frequency channels or subbands. In general, system resources (e.g., frequency subbands/channels, time slots, etc.) to be reused can be divided into usable and forbidden sets. As described above, forbidden sets of adjacent sectors/cells overlap each other. Each sector may form a restricted set based on its available set and the forbidden set of neighboring sectors/cells, as described above.

Restrictive reuse may be used for a global system for mobile communications (GSM) system. The GSM system may operate on one or more frequency bands. Each frequency band covers a particular frequency range and is divided into a plurality of 200kHz Radio Frequency (RF) channels. Each RF channel is identified by a specific ARFCN (absolute radio frequency channel number). For example, GSM 900 bands cover ARFCNs 1-124, GSM 1800 bands cover ARFCNs 512-885, and GSM 1900 bands cover ARFCNs 512-810. Typically, each GSM cell is assigned a set of RF channels and only transmits on the assigned RF channels. To reduce inter-cell interference, GSM cells, which are typically close to each other, are assigned different sets of RF channels so that transmissions of neighboring cells do not interfere with each other. GSM typically uses a reuse factor greater than 1 (e.g., K-7).

For GSM systems, restrictive reuse may be used to improve efficiency and reduce inter-cell interference. The available RF channels of the GSM system may be used to form K usable and forbidden set pairs (e.g., K7), and each GSM cell may be assigned one of the K set pairs. Each GSM cell may then allocate RF channels in its available set to users in the cell and RF channels in its restricted set to weak users. Restrictive reuse allows a larger percentage of the available RF channels to be used per GSM cell and a reuse factor close to one may be achieved.

Restrictive reuse may also be used in multi-carrier communication systems that use multiple "carriers" for data transmission. Each carrier is a sinusoidal signal that is independently modulated with data and is associated with a particular bandwidth. One such system IS a multi-carrier IS-856 system (also known as 3x-DO (for data only)) with multiple 1.23MHz carriers. Each sector/cell in the system can use all carriers or a subset of the carriers. One sector/cell may be prohibited from using a given carrier to avoid causing interference to the carrier, which causes other sectors/cells using the carrier to observe little (or no) interference, achieve higher SINR, and obtain better performance. Alternatively, one sector/cell may be constrained to use a lower transmit power limit on a given carrier, thereby reducing interference on that carrier. For each sector, a restricted (disabled or restricted use) carrier may be assigned statically or dynamically.

Each sector may assign its available carrier(s) to its users. Each sector may also assign carriers to each user in a manner to avoid forming strong interferers/strong interferers to the user. For example, if multiple available carriers are available, a user may be assigned one of the carriers that has less interference to the user (e.g., a carrier that is not used by a strong interferer is assigned to the user).

The processing for data transmission and reception with restrictive reuse depends on the system design. For clarity, an exemplary transmitting and receiving entity in a frequency hopping OFDMA system is described below for a restrictive reuse embodiment with a pair of usable and forbidden subband sets per sector.

Fig. 9 shows a block diagram of an embodiment of a transmitting entity 110x, which may be a transmitting part of a base station or a terminal. Within transmitting entity 110x, an encoder/modulator 914 receives traffic/packet data from a data source 912 for a given user u, processes (e.g., encodes, interleaves, and modulates) the data based on the coding and modulation schemes selected for user u, and provides data symbols, which are modulation symbols for the data. Each modulation symbol is a complex value of a point in a signal constellation of the selected modulation scheme. Symbol-to-subband mapping component 916 provides the data symbols for user u onto the appropriate subbands determined by the FH control generated by FH generator 940 based on the traffic channel assigned to user u. The FH generator 940 may be implemented by a look-up table, a pseudo-random code (PN) generator, or the like. Mapping component 916 also provides pilot symbols on the subbands used for pilot transmission, assigning a signal value of zero to each subband not used for pilot or data transmission. Mapping component 916 provides N transmit symbols for a total of N subbands for each OFDM symbol period, where each transmit symbol may be a data symbol, a pilot symbol, or a signal value of zero.

An OFDM modulator 920 receives the N transmit symbols for each OFDM symbol period and generates corresponding OFDM symbols. OFDM modulator 920 generally includes an Inverse Fast Fourier Transform (IFFT) component and a cyclic prefix generator. For each OFDM symbol period, the IFFT component transforms the N transmit symbols to the time domain using an N-point inverse FFT to obtain a "transformed" symbol that contains N time-domain chips. Each chip is a complex value to be transmitted in one chip period. A cyclic prefix generator then repeats a portion of each transformed symbol to form an OFDM symbol comprising N + C chips, where C is the number of chips repeated. The repeated portion is commonly referred to as a cyclic prefix and is used to overcome inter-symbol interference caused by frequency selective fading. An OFDM symbol period corresponds to the duration of one OFDM symbol, which is N + C chip periods. An OFDM modulator 920 provides a stream of OFDM symbols. A transmitter section (TMTR)922 processes (e.g., converts to analog, filters, amplifies, and frequency upconverts) the OFDM symbol stream to generate a modulated signal, which is transmitted by an antenna 924.

Controller 930 manages operations at transmitting entity 110 x. A memory 932 is used to store program codes and data used by controller 930.

Fig. 10 shows a block diagram of an embodiment of a receiving entity 120x, which may be a receiving part of a base station or a terminal. The one or more modulated signals transmitted by the one or more transmitting entities are received by an antenna 1012, and the received signal is provided to a Receiver Component (RCVR)1014 and processed by it to obtain samples. The set of samples for one OFDM symbol period represents one received OFDM symbol. An OFDM demodulator (Demod)1016 processes the samples and provides received symbols, which are noise estimates of the transmitted symbols sent by the transmitting entity. OFDM demodulator 1016 typically includes a cyclic prefix removal component and an FFT component. A cyclic prefix removal component removes the cyclic prefix in each received OFDM symbol to obtain a received transformed symbol. The FFT section transforms each received transformed symbol to the frequency domain using an N-point FFT to obtain N received symbols for the N subbands. Subband-to-symbol demapping element 1018 obtains the N received symbols for each OFDM symbol period and provides the received symbols for the subbands assigned to user u. These subbands are determined by FH controls generated by FH generator 1040 based on the traffic channel assigned to user u. Demodulator/decoder 1020 processes (e.g., demodulates, deinterleaves, and decodes) the received symbols for user u and provides the decoded data to a data sink 1022 for storage.

Controller 1030 is configured to manage operations at receiving entity 120 x. A memory component 1032 is used to store program codes and data used by controller 1030.

For restrictive reuse, each sector (or scheduler in the system) selects users for data transmission, identifies strong interferers/strong interferers for the selected users, determines an available or restricted set for each selected user based on their strong interferers/strong interferers (if any), and allocates subbands (or assigns traffic channels) from the appropriate set to the selected users. Each sector then provides each user with its assigned traffic channel, e.g., via over-the-air signaling. The transmitting and receiving entities of each user then perform the appropriate processing to transmit and receive data on the subbands represented by the assigned traffic channel.

The restrictive reuse techniques described herein may be implemented in a variety of ways. For example, these techniques may be implemented in hardware, software, or a combination thereof. For a hardware implementation, the processing components for identifying strong/strong interferers, determining restricted sets, allocating subbands, processing data for transmission or reception, and performing other functions related to restrictive reuse may be implemented within one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic components for performing the functions described herein, or a combination thereof.

For a software implementation, the restrictive reuse techniques may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory component (e.g., memory component 932 in fig. 9 or memory component 1032 in fig. 10) and executed by a processor (e.g., controller 930 in fig. 9 or controller 1030 in fig. 10). The memory component may execute within the processor or external to the processor.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (43)

1. A method for allocating system resources in a wireless communication system, comprising:

for each terminal of at least one terminal in communication with a current base station, identifying a strong interference entity for each terminal when the strong interference entity exists, wherein each strong interference entity is an entity seeking to mitigate interference therewith; and

when the strong interference entity exists, allocating system resources to the at least one terminal based on the identified strong interference entity for the at least one terminal.

2. The method of claim 1, wherein each strong interference entity for each terminal is another base station deemed to cause strong interference to the terminal on a forward link.

3. The method of claim 1, wherein each strong interference entity for each terminal is another base station deemed to observe strong interference from the terminal on a reverse link.

4. The method of claim 1, wherein each strong interference entity for each terminal is another terminal deemed to cause strong interference to the terminal on a reverse link.

5. The method of claim 1, wherein for each terminal, unused system resources of the strong interference entity identified for the terminal are allocated to the terminal when the strong interference entity is present.

6. The method of claim 1, wherein the current base station is assigned a set of available system resources and a set of unavailable system resources, and wherein the system resources allocated to the at least one terminal are taken from the set of available system resources.

7. The method of claim 6, wherein each strong interfering entity is associated with a set of system resources not used by the strong interfering entity.

8. The method of claim 7, further comprising:

for each of the at least one terminal, determining a set of system resources available to the each terminal based on the set of available system resources assigned to the current base station and based on a set of system resources not used by the strong interference entity identified for the terminal when the strong interference entity exists, wherein the system resources in the set of system resources available to the each terminal are allocated to the terminal.

9. The method of claim 8, wherein for each terminal, the set of system resources available to the each terminal is determined based on an intersection operation between the set of available system resources assigned to the current base station and each of the set of system resources not used by the strong interfering entity identified for the terminal when the strong interfering entity exists.

10. The method of claim 7, further comprising:

determining a list of resource sets for each of the at least one terminal, wherein the resource sets in the list for each terminal are formed based on different combinations of available sets of system resources assigned to the current base station and sets of system resources not used by the strong interfering entity identified for the terminal when the strong interfering entity is present, and wherein the terminals are allocated system resources from the set of resources within the list determined for each terminal.

11. The method of claim 10, wherein the sets of resources in the list for each terminal are ordered so as to reduce interference caused by or observed by the terminal, and wherein system resources in one or more of the ordered sets of resources within the list determined for each terminal are allocated to the terminal.

12. The method of claim 1, wherein the current base station is assigned a set of available system resources and a set of constrained system resources, and wherein full transmit power is used for the available system resources and reduced transmit power is used for the constrained system resources.

13. The method of claim 1, wherein, for each terminal, when the strong interference entity is present, each terminal is associated with a set containing the strong interference entity identified for the terminal.

14. The method of claim 1, wherein each strong interference entity for each terminal is determined based on a signal quality metric achieved by the terminal for the strong interference entity.

15. The method of claim 1, wherein each strong interference entity for each terminal is determined based on received pilot power measured at the terminal for the strong interference entity.

16. The method of claim 1, wherein each strong interference entity for each terminal is determined based on a channel gain between the terminal and the strong interference entity.

17. The method of claim 1, wherein each strong interference entity for each terminal is determined based on a signal to interference and noise ratio (SINR) achieved by the terminal for the strong interference entity.

18. The method of claim 1, wherein system resources allocated to the at least one terminal are used for data transmission on a reverse link.

19. The method of claim 1, wherein system resources allocated to the at least one terminal are used for data transmission on a forward link.

20. The method of claim 1, wherein the wireless communication system utilizes Orthogonal Frequency Division Multiplexing (OFDM), and wherein the system resources allocated to the at least one terminal are frequency subbands obtained through OFDM.

21. The method of claim 1, wherein the system resources allocated to the at least one terminal are Radio Frequency (RF) channels.

22. The method of claim 1, wherein the wireless communication system is an Orthogonal Frequency Division Multiple Access (OFDMA) system utilizing frequency hopping.

23. A method of allocating frequency subbands in a wireless communication system using Orthogonal Frequency Division Multiplexing (OFDM), the method comprising:

for each terminal of at least one terminal in communication with a current base station, identifying a strong neighbor base station for each terminal when the strong neighbor base station exists;

for each terminal in the at least one terminal, determining a set of frequency subbands usable by the each terminal based on a set of available frequency subbands assigned to the current base station and based on a set of frequency subbands not used by the strong neighboring base station identified for the terminal when the strong neighboring base station exists; and

and allocating the selected frequency sub-band in the frequency sub-band set available for each terminal in the at least one terminal to the terminal.

24. The method of claim 23, wherein each strong neighboring base station for each terminal is a base station deemed to cause strong interference to the terminal, observe strong interference from the terminal, or both cause and observe strong interference from the terminal.

25. The method of claim 23, wherein for each strong neighboring base station for each terminal, the strong neighboring base station is identified for each terminal based on received pilot power measured at the terminal for the strong neighboring base station.

26. An apparatus for allocating system resources in a wireless communication system, comprising:

controller of

For each terminal of at least one terminal in communication with a current base station, identifying a strong interference entity for each terminal when the strong interference entity exists, wherein each strong interference entity is an entity seeking to mitigate interference therewith; and

when the strong interference entity exists, allocating system resources to the at least one terminal based on the identified strong interference entity for the at least one terminal.

27. The apparatus of claim 26, wherein for each terminal, unused system resources of the strong interference entity identified for the terminal are allocated to the terminal when the strong interference entity is present.

28. The apparatus of claim 26, wherein each strong interference entity for each terminal is a base station deemed to cause strong interference to the terminal, observe strong interference from the terminal, or both cause and observe strong interference from the terminal.

29. The apparatus of claim 26, wherein for each strong interference entity for each terminal, the strong interference entity is identified for the each terminal based on received pilot power measured at the terminal for the strong interference entity.

30. The apparatus of claim 26, wherein the controller is further configured to:

for each terminal of the at least one terminal, determining a set of system resources available to the each terminal based on a set of available system resources assigned to the current base station and based on a set of system resources not used by the strong interference entity identified for the terminal when the strong interference entity is present; and

and allocating system resources in the system resource set available for each terminal to the terminal.

31. An apparatus for allocating system resources in a wireless communication system, comprising:

means for identifying, for each terminal of at least one terminal communicating with a current base station, a strong interference entity when present for said each terminal, wherein each strong interference entity is an entity seeking to mitigate interference therewith; and

means for allocating, for the at least one terminal, system resources to the terminal based on the strong interference entity identified for the terminal when the strong interference entity is present.

32. The apparatus of claim 31, wherein for each terminal, when the strong interference entity is present, the terminal is allocated system resources unused for the strong interference entity identified for the terminal.

33. The apparatus of claim 31, further comprising:

means for determining, for each of the at least one terminal, a set of available system resources assigned to the current base station based on the set of available system resources assigned to the current base station and based on a set of system resources not used by the strong interference entity identified for the terminal when the strong interference entity is present, wherein the terminal is allocated system resources from the set of system resources available to the terminal.

34. A method of processing data in a wireless communication system, comprising:

obtaining system resource allocation of a terminal, wherein the terminal communicates with a current base station and allocates unused system resources of the strong interference entity identified for the terminal to the terminal when the strong interference entity exists, and wherein each strong interference entity is an entity seeking to reduce interference with the terminal; and

generating a control indicative of system resources allocated to the terminal.

35. The method of claim 34, wherein the current base station is assigned a set of available system resources, wherein each strong interfering entity is associated with a set of system resources not used by the strong interfering entity, wherein the set of system resources available to the terminal is determined based on the set of available system resources assigned to the current base station and based on the set of system resources not used by the strong interfering entity identified for the terminal when the strong interfering entity is present, and wherein the terminal is allocated system resources from the set of system resources available to the terminal.

36. The method of claim 34, further comprising:

receiving a data transmission sent using system resources allocated to the terminal; and

and processing the received data transmission according to the control.

37. The method of claim 34, further comprising:

processing data for transmission according to the control; and

sending a data transmission using the system resources allocated to the terminal.

38. The method of claim 34, wherein the system utilizes Orthogonal Frequency Division Multiplexing (OFDM), and wherein the system resources allocated to the terminal comprise one or more frequency subbands.

39. The method of claim 38, wherein the system uses frequency hopping, and wherein the control indicates different subbands in which data transmission is performed in different time intervals.

40. An apparatus in a wireless communication system, comprising:

a controller for obtaining an allocation of system resources for a terminal, wherein the terminal is in communication with a current base station and, when a strong interfering entity is present, is allocated system resources unused by the strong interfering entity identified for the terminal, and wherein each strong interfering entity is an entity seeking to mitigate its interference with the terminal; and

a generator for generating a control indicative of system resources allocated to the terminal.

41. The apparatus of claim 40, further comprising:

a demodulator for receiving a data transmission sent using system resources allocated to the terminal; and

a processing component for processing the received data transmission according to the control.

42. The apparatus of claim 40, further comprising:

processing means for processing data for transmission in accordance with the control; and

a modulator to transmit a data transmission utilizing the system resources allocated to the terminal.

43. An apparatus in a wireless communication system, comprising:

means for obtaining system resource allocation for a terminal, wherein the terminal is in communication with a current base station and, when a strong interfering entity is present, the terminal is allocated system resources unused by the strong interfering entity identified for the terminal, and wherein each strong interfering entity is an entity seeking to mitigate its interference with the terminal; and

for generating a control indicative of system resources allocated to the terminal.