Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
2001-08-22
2004-02-24
Patel, Ajit (Department: 2664)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S342000
Reexamination Certificate
active
06697347
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to wireless communication, such as provided by systems as specified in 3GPP (Third Generation Partnership Project) Wideband Code Division Multiple Access (WCDMA) release 5, High Speed Downlink Packet Access (HSDPA), but also as provided by other kinds of wireless communications systems providing for packet transmission. More particularly, the present invention relates to the paging of mobile stations communicating with a base station in such communication systems.
BACKGROUND OF THE INVENTION
FIG. 1
illustrates a radio frame that includes a number of complex (in-phase and quadrature) chips divided among fifteen slots. The radio frame may have a duration of ten milliseconds (10 ms) and include 38400 chips. In the Third Generation Partnership Project (3GPP) each such frame is called a Transmission Time Interval (TTI) defining the periodicity at which Transport Block Sets are transferred to the physical layer on the radio interface. Each slot thus includes 2560 chips, which may represent, for example, ten 256-chip symbols (with an SF of 256). Such a frame/slot/chip structure is a feature of the 3GPP, wideband CDMA communication system currently under consideration. The radio signal transmitted by a BS in such a communication system is the sum of spread and scrambled data and control bits and an unscrambled synchronization channel. Data and control bits are typically spread by either bit-wise (in DS-CDMA systems) or block-wise replacement by an orthogonal sequence or sequences, such as Walsh-Hadamard sequences. (This is sometimes called m-ary orthogonal keying.) As noted above, the spread results are then scrambled usually by bit-wise modulo-2 addition of a pseudo-noise (PN) scrambling sequence.
It will be appreciated that the data bits include user information, such as audio, video, and text information, and that the information of different users is made distinguishable, in accordance with CDMA principles, by using distinguishable spreading sequences, such as mutually orthogonal Walsh-Hadamard sequences. In a sense, then, each user's Walsh-Hadamard sequence(s) define that user's communication channel, and thus these distinguishable sequences are said to channelize the user information. The construction of sequences according to their correlation properties is described in U.S. Pat. No. 5,353,352 to P. Dent et al for Multiple Access Coding for Radio Communications and U.S. Pat. No. 5,550,809 to G. Bottomley et al for Multiple Access Coding Using Bent Sequences for Mobile Radio Communications.
It is desirable to provide various types of communication services to meet various consumer demands, such as voice telephony, facsimile, e-mail, video, Internet access, etc. Moreover, it is expected that users may wish to access different types of services at the same time. For example, a video conference between two users would involve both voice and video support. Some services require higher data rates than others, and some services would benefit from a data rate that can vary during the communication.
FIG. 2
depicts a typical tree structure for Walsh-Hadamard sequences, or codes. Levels in the code tree define channelization codes of different lengths, corresponding to different spreading factors. In
FIG. 2
, the root of the tree is indicated by code C
1,1
that has a spreading factor SF=1, level 1 of the tree includes codes C
2,1
and C
2,2
that each have spreading factors of 2, and so forth. At each level, exemplary corresponding sequences, or codes, are indicated. For the root level, the example shown is [1], for level 1, the example codes shown are [1 1] and [1 −1], and so forth. In the notation C
k,i
illustrated, k is the spreading factor SF and the index i simply distinguishes codes at the same level. It will be appreciated that the tree continues to branch as one moves to the right in FIG.
2
and that it is not necessary for the code sequence at the root level to have only one element as illustrated.
All codes in a code tree cannot be used simultaneously in the same cell or other environment susceptible to mutual interference because all codes are not mutually orthogonal; a code can be used if and only if no other code on the path from the specific code to the root of the tree or in the sub-tree below the specific code is used. This means that the number of available channelization codes is not fixed but depends on the rate and spreading factor of each channel in the group of channels that potentially can mutually interfere.
Eligible channelization codes can be allocated randomly from the available eligible codes in the code tree structure for channels of different rates and spreading factors, which is to say that the eligible codes may be allocated without co-ordination between different connections, other than maintaining orthogonality. On the uplink, different users (connections) use different scrambling codes, so all of the spreading codes in a tree can be used for each user without co-ordination among different users. The situation on the downlink could be different because the BS typically uses only one scrambling code for all users (connections). Thus, spreading codes cannot be allocated so freely; co-ordination among users is needed.
In WCDMA based systems high speed data transmission may be enabled, e.g., by means of the so called high speed downlink packet access (HSDPA) technology. The high speed downlink packet access (HSDPA) may include functions such as fast hybrid automatic repeat request (HARQ), adaptive coding and modulation (AMC) and/or fast cell selection (FCS). These functions are known by the skilled person and will thus not be explained in more detail. A more detailed description of these and other function of the HSPDA can be found, e.g., from a third generation partnership project technical report No. 3G TR25.848 release 2000 titled ‘Physical Layer Aspects of UTRA High Speed Downlink Packet Access’. It shall be appreciated that although the HSDPA has been specified for use in the WCDMA, similar basic principles may be applied to other access techniques.
At the present it is assumed that in the high speed downlink packet access (HSDPA) each user equipment receiving data on a high speed downlink shared channel (HS-DSCH) also has an associated dedicated channel (DCH) allocated. The dedicated channel may be mapped to a dedicated physical channel (DPCH) in the physical layer. The DPCH is typically divided into dedicated physical data channel (DPDCH) and dedicated physical control channel (DPCCH) both in the uplink and the downlink. Data such as the power control commands, transport format information, and dedicated pilot symbols are transmitted on the DPCCH. Information such as diversity feedback information may also be transmitted on DPCCH in the uplink. The HS-DSCH may be mapped to one or several high speed physical downlink shared channels (HS-PDSCH) in the physical layer.
The associated dedicated channel is typically provided both in the downlink and the uplink. The dedicated channel is typically used to carry HSDPA related information/signaling as well as other dedicated data such as speech and control data. The user equipment may communicate with several base stations at the same time. For example, the associated dedicated channel may be in soft handover.
In addition to associated dedicated channels, the HS-DSCH may be associated also with a shared control channel (SCCH). The SCCH can be used to carry HS-DSCH specific information/signaling to those users receiving data on the HS-DSCH.
A current proposal is to use the dedicated channel to inform the user equipment that it has data to be read on the HS-DSCH and SCCH. That is, only those users receiving data at a given time will receive an indication on the dedicated channel. The dedicated channel may be called as a pointer channel since it points to the shared channels. The dedicated channel may also contain information about modulation and coding schemes, power levels and similar parameters used f
Malkamäki Esa
Östman Kjell
Nokia Mobile Phones Ltd.
Patel Ajit
Ware Fressola Van Der Sluys & Adolphson LLP
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