Embodiments of the invention relate to wireless communications; more specifically, to frequency allocation for uplink transmissions based on resource block interlacing.
The Fifth Generation New Radio (5G NR) is a telecommunication standard for mobile broadband communications. 5G NR is promulgated by the 3rd Generation Partnership Project (3GPP) to significantly improve on performance metrics such as latency, reliability, throughput, etc. 5G NR supports operations in unlicensed spectrum (NR-U) to provide bandwidth in addition to the mmWave spectrum to mobile users.
In Long Term Evolution (LTE) or Fourth Generation (4G), the 3GPP defined a coexistence path for WiFi and LTE using the unlicensed spectrum (e.g., 2.4 or 5 GHz bands). LTE provides License-Assisted Access (LAA) and enhanced LAA (eLAA), which leverage the unlicensed 5 GHz band in combination with licensed spectrum to deliver a performance boost in downlink (DL) and uplink (UL), respectively. The unlicensed spectrum for 5G NR may potentially include 6 GHz band, covering 5.925 GHz-7.125 GHz, in addition to the LTE unlicensed spectrum. However, it is noted that the unlicensed spectrum in different countries and regions may deviate from what is mentioned above.
Operation in the unlicensed spectrum is subject to power emission requirements that limit signal propagation and in-band interference. One measurement of power emission is Power Spectral Density (PSD). According to the European Telecommunications Standards Institute (ETSI) regulation, in the 5 GHz band, the maximum PSD with transmit power control is 10 dBm/MHz. Furthermore, the ETSI requires that the Occupied Channel Bandwidth (OCB) be between 80% and 100% of the nominal channel bandwidth in the unlicensed 5 GHz band, where the OCB is defined as the bandwidth containing 99% of the signal power.
Imposing the maximum PSD and OCB requirements on 5G terminals can reduce signal interference and promote efficient usage of the bandwidth in the unlicensed spectrum. However, the maximum PSD requirement on a 5G terminal's transmit power significantly constraints its coverage area. Thus, there is a need for addressing the power emission issue for a 5G terminal in the context of established designs for shared usage of the unlicensed spectrum.
In one embodiment, a method is provided for transmitting an uplink signal in a wireless network that provides an interlace structure in a frequency domain for uplink transmission. The method comprises obtaining a bit sequence which uniquely identifies a user equipment (UE) among a plurality of UEs in the wireless network. The method further comprises identifying a frequency range which is shared by the UEs and is partitioned into N interlaces, N being an integer greater than one. Each interlace is formed by a sequence of resource blocks (RBs) that are non-adjacent and equidistant in frequency. The method further comprises transmitting the uplink signal combined with the bit sequence from the UE to a base station in the wireless network. The transmitted uplink signal spreads across all of the N interlaces.
In another embodiment, a method performed by a UE in a wireless network is provided. The wireless network provides an interlace structure in a frequency domain for uplink transmission. The method comprises identifying a frequency range which is shared by a plurality of UEs and is partitioned into N interlaces, N being an integer greater than one. Each interlace is formed by a sequence of RBs that are non-adjacent and equidistant in frequency. The method further comprises transmitting an uplink signal using a different one of the N interlaces in each of N consecutive symbol periods.
In other embodiment, a UE in a wireless network is provided. The wireless network provides an interlace structure in a frequency domain for uplink transmission. The UE comprises an antenna; a transceiver coupled to the antenna; one or more processors coupled to the transceiver; and memory coupled to the one or more processors. The UE is operative to perform one or more of the aforementioned methods.
Other aspects and features will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.
The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that different references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of this description. It will be appreciated, however, by one skilled in the art, that the invention may be practiced without such specific details. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation.
Disclosed herein are frequency allocation schemes for uplink transmission in the context of interlace structures provided by a wireless network system. The interlace structures promote efficient usage of the bandwidth to thereby satisfy the aforementioned OCB requirement. The disclosed schemes are built on top of the interlace structures for allocating interlaces to UEs such that the UEs can boost their transmit power for uplink transmission while satisfying the aforementioned OCB and maximum PSD requirements.
In one embodiment, the frequency range in connection with the disclosed frequency allocation schemes is in the unlicensed spectrum of a wireless network system. The specific frequency bands of the unlicensed spectrum may differ from one region to another, and may change with the continuous development of the wireless technologies. Thus, it should be understood that the disclosed schemes are not tied to a particular frequency band. The disclosed schemes are provided to comply with the aforementioned OCB and maximum PSD requirements in a wireless network which provides interlace structures in the frequency domain for its users. In some embodiments, such a wireless network may operate according to standards based on 5G NR, LTE, eLAA and/or the like.
The disclosed frequency allocation schemes may be applied to uplink transmissions from a UE to a base station (known as gNodeB in a 5G network). In some examples, uplink transmissions may include transmissions of uplink control information, which may further include, for example, acknowledgements or non-acknowledgements of downlink transmissions, or channel state information. Uplink transmissions may also include transmissions of data, reference signals, and/or contention resolution signals. Uplink signals may be modulated by multiple sub-carriers (e.g., waveform signals of different frequencies) according to various radio technologies.
The number and arrangement of components shown in
Referring to
A network controller 110 may be coupled to a set of BSs such as the BSs 120 to coordinate, configure, and control these BSs 120. The network controller 110 may communicate with the BSs 120 via a backhaul.
The network 100 further includes a number of user equipment terminals (UEs), such as UEs 150a, 150b, 150c and 150d, collectively referred to as the UEs 150. The UEs 150 may be anywhere in the network 100, and each UE 150 may be stationary or mobile. The UEs 150 may also be known by other names, such as a mobile station, a subscriber unit, and/or the like. Some of the UEs 150 may be implemented as part of a vehicle. Examples of the UEs 150 may include a cellular phone (e.g., a smartphone), a wireless communication device, a handheld device, a laptop computer, a cordless phone, a tablet, a gaming device, a wearable device, an entertainment device, a sensor, an infotainment device, Internet-of-Things (IoT) devices, or any device that can communicate via a wireless medium.
In one embodiment, the UEs 150 may communicate with their respective BSs 120 in their respective cells 130. The transmission from a UE to a BS is called uplink transmission, and from a BS to a UE is called downlink transmission.
Multiple time and frequency configurations are supported by NR. With respect to time resources, a frame may be 10 ms in length, and may be divided into ten subframes of 1 ms each. Each subframe may be further divided into multiple equal-length time slots (also referred to as “slots”), and the number of slots per subframe may be different in different configurations 4 slots per subframe). Each slot may be further divided into multiple equal-length symbol periods (also referred to as symbols), and the number of symbols per slot may be different in different configurations (e.g., 14 symbols per slot). In one embodiment, each symbol period may be used to transmit an Orthogonal Frequency-Division Multiplexing (OFDM) symbol.
With respect to frequency resources, NR supports multiple different subcarrier bandwidths (also referred to as subcarrier spacing); e.g., 15 kHz, 30 kHz, 60 kHz or other subcarrier bandwidths. Contiguous subcarriers are grouped into one RB. In one configuration, one RB contains 12 equally-spaced subcarriers, also referred to as resource elements (REs). Multiple RBs (e.g., 4) form one subchannel.
The frequency range allocated to uplink transmission is structured as multiple interlaces of RBs. In the example of
When a UE requests time-and-frequency resources for uplink transmission, the network (e.g., the base station) may grant the UE one of the interlaces for a period of time. When transmitting signals over one interlace (e.g., ITL1), a UE's OCB is calculated as from the start of RB 0 to the end of RB 9, which is over 80% of the nominal channel bandwidth of the frequency range 220. Thus, the interlace structure 200 is designed for the UEs to satisfy the OCB requirement. According embodiments of the invention to be described below with reference to
In this first embodiment, the frequency range 320 may be allocated to one or more UEs.
It is understood that the examples in
In one embodiment, the frequency range may occupy a portion of the unlicensed spectrum for uplink transmission. The unlicensed spectrum, or some portions thereof, may be partitioned into N interlaces of RBs (N is an integer greater than one). However, in this embodiment each UE in the group uses all of the interlaces in the frequency range and may transmit their respective uplink signals to a base station concurrently in the same symbol periods. The uplink signals from different UEs are separated by the base station using the UE-specific code. In one embodiment, the UE-specific code is generated by the base station and communicated to the UE; in an alternative embodiment, the UE generates the UE-specific code and communicates the code to the base station. The bit sequences used by different UEs in the group may be PN bit sequences. In one embodiment, the bit sequences used by different UEs in the group may be orthogonal or quasi-orthogonal to one another.
In one embodiment, the wireless network is a 5G NR network, and the frequency range is in the unlicensed spectrum according to the definition provided by NR-U. In one embodiment, an example of the wireless network may be the network 100 of
In
In a given symbol period, each interlace is allocated to one UE; and different UEs use different interlaces for uplink transmission. That is, the N interlaces in a given symbol period may be allocated to respective ones of the UEs, with each UE allocated with a different one of the N interlaces. Assume that initially (e.g., at a first symbol period), ITL1 is allocated to UE1, ITL2 is allocated to UE2, ITL3 is allocated to UE3, ITL4 is allocated to UE4 and ITL5 is allocated to UE5. Starting with the initial interlace (ITL1), UE1 transmits an uplink signal using a different one of the five interlaces in each subsequent symbol period. For example, UE1 may use ITL1 in a first symbol period, ITL2 in a second symbol period, ITL3 at a third symbol period, ITL4 in a fourth symbol period, and ITL5 in a fifth symbol period. The uplink transmission by UE1 uses N interlaces in N symbol periods (N=5 in the example), but only one interlace in each symbol period. The interlace usage by UE1 follows a cyclic pattern which repeats every N symbol periods.
In one embodiment, the interlace structure provided by a wireless network system may have the same number of RBs for all interlaces in a given frequency range. In another embodiment, the interlace structure provided by a wireless network system may have different numbers of RBs for different interlaces in a given frequency range. That is, at least one of the N interlaces may have a different number of RBs from the others of the N interlaces. In the example of
It is noted that the time and the frequency allocated to uplink transmission are not limited to the aforementioned examples. For example, the number of interlaces in a predefined frequency range, the number of RBs in each interlace, and/or the number of symbols per cycle in the cyclic pattern of
In one embodiment, the UE uses a different one of the N interlaces for the uplink transmission according to a cyclic pattern which repeats every fixed interval; e.g., every N symbol periods.
In one embodiment, the wireless network is a 5G NR network, and the frequency range is in the unlicensed spectrum according to the definition provided by NR-U. In one embodiment, an example of the wireless network may be the network 100 of
The frequency allocation schemes described above in connection with
Although the UE 700 is used in this disclosure as an example, it is understood that the methodology described herein is applicable to any computing and/or communication device capable of transmitting uplink signals to a base station.
The operations of the flow diagrams of
Various functional components or blocks have been described herein. As will be appreciated by persons skilled in the art, the functional blocks will preferably be implemented through circuits (either dedicated circuits, or general-purpose circuits, which operate under the control of one or more processors and coded instructions), which will typically comprise transistors that are configured in such a way as to control the operation of the circuitry in accordance with the functions and operations described herein.
While the invention has been described in terms of several embodiments, those skilled in the art will recognize that the invention is not limited to the embodiments described, and can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is thus to be regarded as illustrative instead of limiting.
This application claims the benefit of U.S. Provisional Application No. 62/737,996 filed on Sep. 28, 2018, the entirety of which is incorporated by reference herein.
Number | Date | Country | |
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62737996 | Sep 2018 | US |