Method to perform joint scheduling in the downlink or in the uplink of a centralized OFDM radio access network for a plurality of users considering time, frequency and space domains, scheduler device thereof and computer program products

Patent metadata

Field	Value
Publication number	US-10153874-B2
Application number	US-201615334680-A
Country	US
Kind code	B2
Filing date	Oct 26, 2016
Priority date	Oct 27, 2015
Publication date	Dec 11, 2018
Grant date	Dec 11, 2018

Abstract

Method to perform joint scheduling in the downlink or in the uplink of a centralized OFDM radio access network for a plurality of users considering time, frequency and space domains, scheduler device thereof and computer program products. The method to be applied in the downlink or in the uplink of a centralized radio access network based on OFDM, whereby a set of remote radio heads of a set of remote units are connected to a central unit, that performs all (or part of) the radio-related processing tasks, wherein the scheduling exploit CoMP, NOMA and RF conditions and resource blanking techniques.

First claim

The invention claimed is:

1. A method to perform joint scheduling in the downlink of a centralized OFDM radio access network for a plurality of users considering time, frequency and space domains, said scheduling being executed at a central unit, CU, of the centralized OFDM radio access network comprising a number M of remote units, RUs, and a number N of users, said CU having complete knowledge of channel quality characteristics at n different frequency subbands for said number N of users, wherein the scheduling being for a maximum of K subbands at arbitrary frequency locations for each remote unit, RU, of said number M of RU and wherein the scheduling exploiting Coordinated Multi Point, CoMP, Non-Orthogonal Multiple Access, NOMA, and Radio Frequency, RF, isolation conditions, and resource blanking techniques,
characterized in that the method comprises the following steps:
a) initializing values user(i, k)=−1 for all values of i and k, and S i ={Ø}, wherein user(i, 0), user(i, 1), . . . , user(i, n−1) denote the set of users which will be assigned subbands 0, 1, . . . , n−1 at RU i, and S i denotes the set of users that have already been scheduled a total of K subbands at RU i according to the expression:
S i ={j∈[ 0, N− 1]: j =user( i,k 0 ), . . . , j =user( i,k K-1 ) for k 0 ,k 1 . . . ,k K-1 ∈[0, n− 1]};

b) calculating scheduling metrics T ijk corresponding to RU i, user j and subband k according to a given criterion, and constructing a three-dimensional metrics table of size N×n×M containing said scheduling metrics;
c) storing channel quality indicators, CQI ijk , associated to RU i, user j and subband k, said channel quality indicators representing a measure of the channel quality as perceived by the users;
d) selecting, for each time instant, a random subband k and RU i among a set of subbands and RUs not yet assigned by the method;
e) finding a user j 0 with the highest metric T ijk for RU i and subband k among the users not belonging to S i according to the expression:

j
0

=

argmax

j
∉

S
i

⁢

{

T
ijk

}

,

wherein if several maxima are found, the user j 0 is chosen randomly among a number of users j 0 fulfilling said maxima;
f) analyzing whether there is another RU i′ for which user j 0 has a higher maximum value of the metric T ijk for the same subband k, and in that case then considering RU i′ rather than RU i for association with user j 0 , otherwise considering RU i;
g) checking, for the selected RU i, whether there is another user j 0 ′ already scheduled in the same subband as j 0 , and in the affirmative case:
g1) deciding whether CoMP can be employed in that subband, and if CoMP can be employed, and if the number of already coordinated users is lower than L, then automatically scheduling for user j 0 the same set of subbands scheduled for user j 0 ′, wherein L denotes the size of the CoMP cluster; or
g2) crossing out all the metric values for user j 0 and the RUs involved in the coordination in the three-dimensional metrics table, for the set of subbands scheduled for user j 0 ′, and if the number of already coordinated users is equal to L then all metric values will be crossed out for all the remaining users at the same set of subbands and RUs involved in the coordination;

h) if there is no other user j 0 ′ already scheduled in the same subband as j 0 for the selected RU, analyzing whether there is another subband l≠k for which user j 0 has a higher maximum value of the metric T ijk , and
in the affirmative case, secondary maxima of the metric values are sought for both subbands, namely:

j
1

=

argmax

j
∉

S
i

,

j
≠

j
0

⁢

{

T
ijk

}

j
2

=

argmax

j
∉

S
i

,

j
≠

j
0

⁢

{

T
ijl

}

,

and if T ij 1 k +T ij 0 l >T ij 0 k +T ij 2 l then assigning user j 1 to subband k and user j 0 to subband l, otherwise assigning user j 0 to subband k and user j 2 to subband l;
if there is no other subband l≠k for which user j 0 has a higher maximum value of the metric T ijk , assigning user j 0 to subband k;
i) analyzing whether the assigned subband(s) can also be scheduled at a different RU i′ in CoMP, NOMA or RF isolation conditions, by:
i1) deciding whether CoMP can be employed for a given RU i′≠i, and in such a case and if the number of already coordinated RUs for user j is lower than L, then applying CoMP techniques so that the same user and subbands will be scheduled at RUs i and i′;
i2) deciding whether NOMA can be employed for a given RU i′≠i, and in such a case then applying NOMA for RUs i and i′ and users j and j′ at subband k, thereby sharing resources for both users at both RUs, and crossing out and any other entries in the three-dimensional table corresponding to RUs i and i′ for subband k and users other than j and j′;
i3) deciding whether there is sufficient RF isolation between RUs i and i′ for subband k and a given RU i′, and in such a case then RUs i and i′ will be considered sufficiently isolated for user j, and subband k can be reused for those RUs; and
i4) crossing out any entries in the three-dimensional metrics table corresponding to RUs for which the above three conditions (i1-i3) are not met at the assigned subband k for user j, thereby muting transmissions from interfering RUs for all users j at resources wh

Assignees

• Telefonica Sa

Inventors

• Lorca Hernando Javier

Classifications

• H04W72/542

  using measured or perceived quality · CPC title

• H04L1/0027

  Scheduling of signalling, e.g. occurrence thereof · CPC title

• H04L5/0057

  Physical resource allocation for CQI · CPC title

• H04L5/0075

  Allocation using proportional fairness · CPC title

• H04L5/0037

  Inter-user or inter-terminal allocation · CPC title